b6 inheritance variation and name: evolution · 2018-03-27 · use evidence from the graphic above...

B6 Inheritance Variation andEvolutionPractice questions

Name: ________________________

Class: ________________________

Date: ________________________

Time: 181 minutes

Marks: 177 marks

Comments: FOUNDATION TIER

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Figure 1 shows a fish called a carp.

Figure 1

The characteristics of an animal can be a result of:

• only genetic causes

• only environmental causes

• both genetic and environmental causes.

(a) Give one characteristic shown in Figure 1 for each different cause.

Only genetic causes _________________________________________________

Only environmental causes ____________________________________________

Both genetic and environmental causes __________________________________

___________________________________________________________________

(3)

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(b) Two alleles control the body colour of carp:

• brown ( B)

• blue ( b).

The brown allele is dominant to the blue allele.

The genetic cross from breeding two carp is shown in Figure 2.

Figure 2

Complete Figure 2.

(2)

(c) Draw a ring around one blue offspring shown in Figure 2.

(1)

(d) What is the probability that the offspring from this genetic cross will be brown?

Tick two boxes.

0

0.25

0.5

1.0

(1)

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(e) Carp can produce large numbers of offspring.

The two carp crossed in Figure 2 had 260 000 offspring.

Approximately how many offspring are expected to be brown?

___________________________________________________________________

Brown carp offspring = ___________________

(1)

(f) A pond contains carp used for breeding.

The carp for breeding are brown or blue.

A red carp has been seen.

The red carp was not added to the pond.

Suggest what might have caused the red carp to appear.

___________________________________________________________________

___________________________________________________________________

(1)

(Total 9 marks)

Living things can be classified into groups.

(a) Scientists look at structures inside cells to classify living things.

Suggest one structure found in cells that can be used to classify living things.

___________________________________________________________________

(1)

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(b) The table below shows one system for classifying humans.

X Animalia

Phylum Chordata

Class Mammalia

Order Primates

Family Hominidae

Genus Homo

Species Sapiens

Who devised this system of classification?

Tick one box.

Darwin

Linnaeus

Wallace

Woese

(1)

(c) Look at the table above.

X is the largest category in this classification.

Name category X.

___________________________________________________________________

(1)

(d) Give the binomial name of humans.

Use information in the table above.

___________________________________________________________________

(1)

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(e) Suggest one way that classification systems are useful to scientists.

___________________________________________________________________

(1)

(Total 5 marks)

(a) Some antibiotics work by destroying the cell membranes of bacteria.

Suggest why these antibiotics may have side effects in the animals that are given theseantibiotics.

___________________________________________________________________

(1)

3

(b) Each arrow on the figure below shows the date of discovery of each new type of antibiotic.

In which 10 year period were most new types of antibiotic discovered?

___________________________________________________________________

(1)

(c) The figure above shows 22 new types of antibiotic. These were discovered before 2010.

Determine the percentage of types of antibiotic that have been discovered between 1980and 2010.

Use information from the figure above.

Give your answer to 2 significant figures.

___________________________________________________________________

___________________________________________________________________

____________________ %

(2)

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(d) Bacteria can evolve rapidly.

Many bacteria can develop into new strains which are resistant to antibiotics.

Complete the table below to show if each action is more likely or less likely to helpbacteria to become antibiotic resistant.

Put a tick in each row.

Action More likely Less likely

Take painkillers for headache

Washing with antiseptic hand gel

Adding antibiotics to food for cows

Giving antibiotics for colds and flu

Stopping antibiotics as soon as you feel better

(4)

(Total 8 marks)

Sexual reproduction in humans involves the joining together of an egg cell and a sperm cell.

The sex of an embryo is decided by the chromosomes they inherit from their mother and father.

(a) Where in the cell are the chromosomes?

Tick one box.

Cell membrane

Cytoplasm

Nucleus

Ribosomes

(1)

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(b) Draw one line from each type of cell to the number of chromosomes in the cell.

Type of cell Number of

chromosomes

23

Sperm cell 26

46

Embryo cell 52

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(2)

(c) A man and a woman decide to have a child.

Complete the genetic diagram in the figure below.

(2)

(d) On the figure above, circle a male child.

(1)

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(e) What is the chance of the man and woman having a boy?

Tick one box.

1 in 2

1 in 3

1 in 4

1 in 8

(1)

(Total 7 marks)

A person’s characteristics can be due to:

• environmental causes

• genetic causes

• both environmental and genetic causes.

(a) Complete Table 1.

Put a tick to show what each characteristic is due to.

Table 1

Characteristic

Characteristic due to

Environmentalcauses

Genetic causesBoth environmental and

genetic causes

Eye colour

A scar

Weight

(3)

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(b) Draw one line from each key term to the correct definition.

Key term Definition

The set of alleles for a characteristic

Genotype The genus of an organism

The inheritance of chromosomes

Phenotype The mutation of genes

The physical characteristic of an organism

(2)

(c) Farmers use selective breeding to control the characteristics in cows.

Table 2 shows the stages of selective breeding in cows.

Complete Table 2 to show the correct order of the stages.

The first stage has been numbered for you.

Table 2

Stage in selective breeding Order of stage

Cows are bred over many generations

Parents are bred together

Cows with the desired characteristics are chosen 1

Calves with the most desired characteristics are bred together

(2)

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(d) Farmers selectively breed cows for many different reasons.

Suggest two characteristics that cows may be bred for.

Do not suggest coat colour.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

(2)

(e) Selective breeding can lead to problems.

Suggest how problems caused by selective breeding in cows can have negative financialeffects for the farmer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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(2)

(Total 11 marks)

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Genetic disorder E is a condition caused by a change in the chromosomes.

(a) Figure 1 shows the chromosomes from one cell of a person with genetic disorder E.

(i) How do you know this person is female?

Use information from Figure 1.

______________________________________________________________

______________________________________________________________

(1)

(ii) Describe how the chromosomes shown in Figure 1 are different from thechromosomes from a person who does not have genetic disorder E.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

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(b) As a woman gets older, the chance of her having a baby with genetic disorder E increases.

Figure 2 shows this.

(i) The chance of a 35-year-old woman having a baby with genetic disorder E is 2 per1000 births.

What is the chance of a 40-year-old woman having a baby with genetic disorder E?

_____________ per 1000 births

(1)

(ii) A 40-year-old woman is more likely than a 35-year-old woman to have a baby withgenetic disorder E.

How many times more likely?

_____________________ times

(1)

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(c) A 41-year-old woman wants to have a baby. A 41-year-old woman has an increasedchance of having a baby with genetic disorder E.

Doctors can screen embryos for genetic disorder E.

The table gives some information about two methods of embryo screening.

Method 1 Method 2

1. The woman is given hormones to cause the release of a few eggs. The eggs are taken from her body in a minor operation. The eggs are fertilised in a glass dish.

1. The woman gets pregnant in the normal way.

2. One cell is taken from each embryo when the embryo is 3 days old.

2. Cells are taken when the embryo is 10 weeks old.

3. Cells are screened for genetic disorder E.

3. Cells are screened for genetic disorder E.

4. An unaffected embryo is placed in the woman’s uterus. Embryos that are not used are destroyed or used in medical research.

4. An unaffected fetus is allowed to develop. If the fetus has genetic disorder E, the woman can choose to have an abortion.

5. This method costs about £6000. 5. This method costs about £600.

Use information from the table to give two advantages and one disadvantage of Method 1compared with Method 2 for detecting genetic disorder E.

Advantages of Method 1:

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

Disadvantage of Method 1:

___________________________________________________________________

___________________________________________________________________

(3)

(Total 8 marks)

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Fossils give us information about organisms from a long time ago.

(a) Amber is a solid, glass-like material. Amber is formed from a thick, sticky liquid whichoozes out of pine trees.

The image shows two fossil insects in amber.

© fkienas/iStock/Thinkstock

(i) Suggest how the insects came to be preserved in the amber.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(ii) Give two other ways fossils are formed.

1. ____________________________________________________________

______________________________________________________________

2. ____________________________________________________________

______________________________________________________________

(2)

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(b) The fossil record shows that many organisms, including the dinosaurs, became extinct 65million years ago.

One theory was that volcanic activity might have caused this mass extinction. Manyscientists believe that this extinction was caused when an asteroid collided with the Earth.

(i) A new scientific theory may replace an old theory.

Why might this happen?

Tick ( ) one box.

Evidence from amber is unreliable.

Internet evidence is more reliable than fossilevidence.

New technology provides more valid evidence.

(1)

(ii) Give three reasons, other than volcanic activity and collision with an asteroid, why aspecies may become extinct.

1. ____________________________________________________________

______________________________________________________________

2. ____________________________________________________________

______________________________________________________________

3. ____________________________________________________________

______________________________________________________________

(3)

(Total 8 marks)

This question is about evolution in humans.

The graph shows:

• the estimated brain volume of different species of humans

• the time when the different species existed on Earth.

The data is plotted for modern humans (Homo sapiens) and for three types of extinct ancestorsof humans.

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Millions of years ago

KeyEach point plotted on the graph shows the estimate for one human.

(a) (i) As humans evolved, their brain volume changed.

What has happened to human brain volume over the past 4 million years?

______________________________________________________________

______________________________________________________________

(1)

(ii) Why is the evidence for estimated brain volume for Homo sapiens stronger than theevidence for Australopithecus afarensis?

______________________________________________________________

______________________________________________________________

(1)

(b) In a book, the brain volume of a different species, Australopithecus africanus, is stated tobe about 600 cm3.

Use evidence from the graphic above to estimate when Australopithecus africanus lived onEarth.

Estimate = _________________ million years ago

(1)

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(c) Scientists believe that modern humans evolved by natural selection from Australopithecusafarensis.

(i) Complete the following sentence.

In the nineteenth century, the scientist who suggested the theory of evolution bynatural selection was Charles ____________________________ .

(1)

(ii) In the nineteenth century, many people did not accept this scientist’s theory.

Give one reason why.

______________________________________________________________

______________________________________________________________

(1)

(Total 5 marks)

Figure 1 shows a fossil of a sea animal called a Plesiosaur.The Plesiosaur was alive about 135 million years ago.

Figure 1

By Andy Dingley (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)],

via Wikimedia Commons

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(a) How can fossils give evidence for evolution?

Tick ( ) one box.

Newer fossils are simpler than older fossils.

Fossils show change over time.

All fossils show the bones of animals.

(1)

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(b) Plesiosaurs lived in the sea. There was mud at the bottom of the sea.

Suggest how the fossil shown in Figure 1 may have been formed after the animal died.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(3)

(c) Figure 2 shows what scientists think a living Plesiosaur may have looked like.

Figure 2

© Andreas Meyer/Hemera/Thinkstock

Scientists think that the Plesiosaur had smooth skin, with no scales.

The scientists cannot be certain what the skin of a Plesiosaur was like.Suggest why.

___________________________________________________________________

___________________________________________________________________

(1)

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(d) Plesiosaurs are now extinct.

Give two possible reasons why.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

(2)

(Total 7 marks)

In sexual reproduction, an egg fuses with a sperm.

(a) (i) Draw a ring around the correct answer to complete the sentence.

An egg and a sperm fuse together in the process of

cloning.

fertilisation.

mitosis.

(1)

10

(ii) Egg cells and sperm cells each contain the structures given in the box.

chromosome gene nucleus

List these three structures in size order, starting with the smallest.

1 ____________________________________________________ (smallest)

2. ____________________________________________________________

3 _____________________________________________________ (largest)

(2)

(iii) The egg and the sperm contain genetic material.

Draw a ring around the correct answer to complete the sentence.

The genetic material is made of

carbohydrate.

DNA.

protein.

(1)

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(b) The diagram below shows the inheritance of X and Y chromosomes.

(i) Draw a tick ( ) on the part of the diagram that shows a sperm cell.

(1)

(ii) What is the chance of having a female child?

Give the reason for your answer.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(Total 7 marks)

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Starfish can split in half. Each half can then grow new arms to form offspring.

This process is shown in the figure below.

(a) What process produces the starfish offspring?

Tick one box.

Asexual reproduction

Fertilisation

Selective breeding

Sexual reproduction

(1)

11

(b) More cells are produced as the starfish grows more arms.

What process will produce more cells in the starfish as they grow?

___________________________________________________________________

(1)

(c) All the offspring produced are genetically identical.

What name is given to genetically identical organisms?

___________________________________________________________________

(1)

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(d) Each body cell of the parent starfish contains 44 chromosomes.

How many chromosomes are in each body cell of the offspring?

___________________________________________________________________

(1)

(Total 4 marks)

Moose are animals that eat grass.

Figure 1 shows a moose.

Figure 1

© Wildnerdpix/iStock/Thinkstock

Figure 2 shows a food chain.

Figure 2

Grass Moose Wolves

(a) Name the secondary consumer shown in Figure 2.

___________________________________________________________________

(1)

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(b) Figure 3 shows how the moose population and wolf population have changed in one area.

This is a predator-prey cycle.

Figure 3

In 2004 the line on Figure 3 for wolves is above the line for moose.

How does Figure 3 show that there are more moose than wolves in 2004?

___________________________________________________________________

___________________________________________________________________

(1)

(c) Suggest why the moose population decreased between 2002 and 2004.

Use information from Figure 3.

___________________________________________________________________

___________________________________________________________________

(1)

(d) The number of wolves is one biotic factor that could affect the size of the moosepopulation.

Give two other biotic factors that could affect the size of the moose population.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

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(2)

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(e) Moose have distinct characteristics such as antlers.

Describe how moose may have evolved to have large antlers.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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___________________________________________________________________

___________________________________________________________________

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(5)

(Total 10 marks)

Bacteria can cause disease.

Figure 1 shows some features of a Salmonella bacterium.

Figure 1

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(a) Draw one line from each feature of the Salmonella bacterium to the function.

Feature Function

Controls the movement of substances into andout of the cell

Cell membrane

Carries genetic information

Plasmid DNA Provides support and protection

The site of protein synthesis

(2)

(b) How is Salmonella spread between people?

Tick one box.

Animal bites

Contaminated food

Sneezing

Sexual contact

(1)

(c) Give two ways you could stop Salmonella from spreading.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

(2)

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(d) Harmful bacteria can also be useful.

Scientists are doing research to find out if Salmonella can be used in a vaccine to treatcancer.

The Salmonella vaccine can be injected into the blood or swallowed in a tablet.

One benefit of injecting the vaccine is that it gets to the cancer quickly in the blood.

What is another benefit?

Tick one box.

All cancers can be treated by the injection

It will not cause sickness and diarrhoea side effects

The injection is not painful to the patient

The injection introduces cancer cells into the body

(1)

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(e) The Salmonella bacterium used in the vaccine is genetically modified using part of a virus.

Look at Figure 2.

Figure 2

Complete the sentences.

Use the letters from Figure 2.

Bacteria reproduce quickly in part _______________________________________

DNA with the desired gene is removed from the virus in part __________________

The chosen gene is inserted into the plasmid in part ________________________

(3)

(Total 9 marks)

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(a) Which of the following is the best definition of a species?

Tick ( ) one box.

Organisms with many features in common

Organisms that live in the same habitat and eat the same food

Organisms that reproduce together to form fertile offspring

(1)

14

(b) Figure 1 is a photograph of the Grand Canyon.

The layers of rock contain fossils.

© Sumikophoto/iStock/Thinkstock

Scientists found five fossils of different species of animal, P, Q, R, S and T, at the positionsshown in Figure 1.

(i) What is the evidence in Figure 1 that animals P and Q were alive at the sametime?

______________________________________________________________

______________________________________________________________

(1)

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(ii) Was animal R alive at an earlier time or at a later time than animals P and Q?

Give the reason for your answer.

______________________________________________________________

______________________________________________________________

(1)

(iii) Which two of the following would be evidence that animal T may have evolvedfrom animal S?

Tick ( ) two boxes.

The fossils of animals S and T have many features in common,but T is more complex than S.

The fossils of animals S and T are the same size.

The fossils of animals S and T have the same skin colour.

The fossil of animal S was found in a deeper layer of rock thanthe fossil of animal T.

The fossil of animal T is more similar to the fossil of animal Rthan to the fossil of animal S.

(2)

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(c) Figure 2 shows two species of ground squirrel, W and X.

Squirrel W lives on the high ground to the south of the Grand Canyon.

Squirrel X lives on the high ground to the north of the Grand Canyon.

The land to the north of the Grand Canyon is about 300 metres higher than the land on thesouth side. The north side also has lower winter temperatures and has more rain and snowthan the south side.

(i) The two species of squirrel are very similar.

Describe one way, which you can see in Figure 2, in which squirrel X is different fromsquirrel W.

______________________________________________________________

______________________________________________________________

(1)

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(ii) The Grand Canyon was formed about 6 million years ago.

Explain how the two different species of squirrel could have developed from acommon ancestor.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

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(6)

(iii) Squirrels W and X are separate species, but they are still very similar.

Suggest why the two species have not become more different over time.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(Total 14 marks)

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Glyphosate is a herbicide.

Crop plants have been genetically modified to make them resistant to glyphosate.

(a) Why is it an advantage to make crop plants resistant to glyphosate?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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(3)

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(b) Figure 1 shows how scientists produce genetically modified (GM) crop plants.

The scientists use a GM-bacterium that can invade plant cells.

(i) The ring of DNA shown in Figure 1 acts as a vector for the resistance gene.

What is the scientific name for this ring of DNA?

______________________________________________________________

(1)

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(ii) At step 1 in Figure 1, the ring of DNA is cut open.

How do scientists cut open the ring of DNA?

______________________________________________________________

______________________________________________________________

(1)

(iii) At step 5 in Figure 1, plant cells and GM-bacteria are put on agar containingglyphosate.

Explain why the scientists add glyphosate to the agar.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

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(c) Some people disagree with the use of GM herbicide-resistant crop plants.

Figure 2 shows data published on a website in 2013.

A journalist used the data to claim: ‘Scientists show that GM crops cause kidney disease inhumans.’

Use information from Figure 2 to evaluate the evidence for this claim.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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___________________________________________________________________

___________________________________________________________________

(4)

(Total 11 marks)

DNA is the genetic material of human cells.

Figure 1 shows the structure of part of a DNA molecule.

(a) (i) Describe where DNA is found in a human cell.

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(ii) When a cell divides by mitosis the new cells are genetically identical.

What causes the cells to be genetically identical?

______________________________________________________________

______________________________________________________________

(1)

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(b) Many genes have different forms called alleles.

(i) A person has polydactyly (extra fingers or toes). Polydactyly is caused by a dominantallele.What is the smallest number of copies of the dominant allele for polydactyly thatcould be found in a body cell of this person?

______________

(1)

(ii) Another person has cystic fibrosis. Cystic fibrosis (CF) is caused by a recessiveallele.How many copies of the recessive CF allele are there in a body cell of this person?

______________

(1)

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(c) A burglar broke into a house. The burglar cut his hand on some broken glass. Scientistsextracted DNA from the blood on the broken glass.

The scientists analysed the DNA from the glass and DNA from three suspects, A, B and C.The scientists used a method called DNA fingerprinting.

Figure 2 shows the scientists’ results.

Which suspect, A, B or C, is most likely to have been the burglar?

Tick ( ) one box.

A

B

C

(1)

(Total 6 marks)

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The photograph shows a fossil of a prehistoric bird called Archaeopteryx.

By Ghedoghedo (own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/BY-SA-3.0) or GFDL (http://www.gnu.org/copyleft

/fdl.html)], via Wikimedia Commons; By Steenbergs from Ripon, United Kingdom (Small Fishing Boat In North Sea) [CC-BY-2.0

(http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons.

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(a) Describe three ways fossils can be made.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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(3)

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(b) The drawing shows what an Archaeopteryx might have looked like when it was alive.

Scientists think that Archaeopteryx was a predator.

(i) Look at the drawing.

Write down three adaptations that might have helped Archaeopteryx to catch prey.

How would each adaptation have helped Archaeopteryx to catch prey?

Adaptation 1 ___________________________________________________

How it helps ____________________________________________________

______________________________________________________________

Adaptation 2 ___________________________________________________

How it helps ____________________________________________________

______________________________________________________________

Adaptation 3 ___________________________________________________

How it helps ____________________________________________________

______________________________________________________________

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(ii) Archaeopteryx is now extinct.

Give two reasons why animals may become extinct.

1. ____________________________________________________________

______________________________________________________________

2. ____________________________________________________________

______________________________________________________________

(2)

(Total 8 marks)

Some genetic disorders are caused by alleles inherited from the parents.

(a) What are alleles?

___________________________________________________________________

___________________________________________________________________

(1)

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(b) Describe how embryos can be screened for the alleles that cause genetic disorders.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

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(4)

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(c) Polydactyly is a genetic disorder that leads to extra fingers or toes.

Polydactyly is caused by a dominant allele, D.

The photograph shows the hand of a person with polydactyly.

© Adem Demir/Hemera.

A man has polydactyly. His wife does not have polydactyly.

This couple‘s children have a 50% chance of having polydactyly.

Draw a genetic diagram to explain why.

(3)

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(d) Cystic fibrosis is another genetic disorder. It is caused by a recessive allele.

The diagram shows the inheritance of cystic fibrosis in one family.

Woman 5 is pregnant with her fourth child.

What is the probability that this child will have cystic fibrosis?

Draw a genetic diagram to explain your answer.

Use the following symbols.

N = allele for normal health n = allele for cystic fibrosis

(4)

(Total 12 marks)

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The diagram shows part of a DNA molecule.

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(a) (i) In which part of an animal cell is DNA found?

______________________________________________________________

(1)

(ii) Complete the following sentence.

The letters A, C, G and T in the diagram represent four different compounds

called __________________________ .

(1)

(iii) One strand of the DNA, in the section labelled X, contains the following sequence ofthese compounds:

T A T G G G T C T T C G

How many amino acids would this section of the DNA code for?

(1)

(iv) The section of DNA described in part (a) (iii) is a small part of a gene.

The sequence of compounds A, C, G and T in the gene is important.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

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(b) Read the following information about genetic engineering.

The caterpillar of the European Corn Borer moth feeds on the fruits of maize (sweet corn).There is a chemical called Bt-toxin which is poisonous to the corn borer caterpillar but notto humans.

Scientists carried out the following steps.

1. The Scientists made a bacterial plasmid to which they added two genes: • Bt gene, which coded for production of the Bt-toxin • kanr gene, which coded for resistance to an antibiotic called kanamycin.

2. They used this plasmid to produce genetically modified bacteria which could invadeplant cells.

3. They mixed these genetically modified bacteria with pieces cut from maize leaves.

4. They placed the pieces of maize leaf on agar jelly in a Petri dish. The agar jellycontained the antibiotic, kanamycin. The kanamycin killed most of the pieces ofmaize leaf, but a few survived.

5. They took some cells from the surviving pieces of maize leaf and grew them in tissueculture.

The result was maize plants that now contained the Bt gene, as well as the kanr gene, inall of their cells.

(i) What is a plasmid (Step 1)?

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(ii) Why did the scientists add kanamycin to the agar jelly (Step 4)?

______________________________________________________________

______________________________________________________________

______________________________________________________________

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(iii) The scientists grew each Bt-maize plant from a single cell which contained the Btgene.

Explain why all the cells in the Bt-maize plant contained the Bt gene.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(iv) Kanamycin is an antibiotic.

Some scientists are concerned that the gene for kanamycin resistance has been putinto maize.

Suggest why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

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(2)

(Total 13 marks)

CRAM is an inherited condition which causes muscle breakdown.

The breakdown products enter the urine, making it dark-coloured.

The diagram below shows the inheritance of CRAM in one family.

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CRAM is caused by a recessive allele, n.

The allele for normal health is N.

(a) (i) What is an allele?

______________________________________________________________

______________________________________________________________

(1)

(ii) What does recessive mean?

______________________________________________________________

______________________________________________________________

(1)

(iii) Give evidence from the diagram that CRAM is caused by a recessive allele.

______________________________________________________________

______________________________________________________________

(1)

(b) (i) Person 2 is homozygous for CRAM.

What does homozygous mean?

______________________________________________________________

______________________________________________________________

(1)

(ii) None of person 2’s children have CRAM.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

(2)

(c) Persons 7 and 8 want to have another child.

(i) What is the probability that this child will have CRAM?

Draw a genetic diagram to explain your answer.

Probability = _____________________________

(4)

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(ii) To avoid having another child with CRAM, persons 7 and 8 may decide to useembryo screening.

Two ways of doing this are:

• PGD (pre-implantation genetic diagnosis)

• CVS (chorionic villus sampling).

PGD involves IVF (in vitro fertilisation) of a few eggs, then taking a cell from eachembryo when it is 3 days old.

The image below shows how the cell is removed.

© Rtimages/iStock/Thinkstock

The DNA in the cell can then be tested. An unaffected embryo can be implanted inthe woman’s uterus. The possibility of a false positive result is around 1 in 6. Theprocedure costs about £6000. Affected embryos would be discarded. Extraunaffected embryos might be frozen and kept for later implantation. Alternatively, theextra embryos might be used in scientific research.

CVS involves taking a sample of blood from the placenta a few weeks intopregnancy. DNA from white blood cells can then be tested.If an affected embryo is detected, the parents then have to decide whether toterminate the pregnancy or allow it to continue.

CVS has a 1 percent chance of giving an incorrect result and a 0.9 percent chance ofcausing a miscarriage. CVS costs about £600.

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Evaluate the benefits of these two methods of embryo screening.You should include a conclusion to your evaluation.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

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______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(5)

(Total 15 marks)

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Mark schemes

(a) only genetic causesany one from:

• pattern of scales• number of fins• eye colour

1

only environmental causes:

• scar1

both genetic and environmental causes:

• length1

1

(b)

B b

b bb

b Bb bb

allow 2 correct for 1 mark2

(c) any bb circled1

(d) 0.5

allow ecf from 04.21

(e) (260 000 / 2 =) 130 000

allow ecf from 04.41

(f) mutation

allow change in diet / hormones / DNA1

[9]

(a) Relevant organelle found in cells such as nucleus, mitochondria12

(b) Linnaeus1

(c) Kingdom1

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(d) Homo Sapiens

ignore underlining, italics or not, capitals or not1

(e) Any one from:

• to know which species are closely relatedorstudy evolution

• to monitor biodiversity• to identify different organisms such as two different species

1

[5]

(a) animal cells also have cell membrane13

(b) 1945–1955

allow 1946–1956

or 1947–19571

(c)

allow 9.09 (%) or 9 (%) with no working shown for 1 mark1

9.1 (%)

allow 9.1 (%) with no working shown for 2 marks1

(d)

More likely Less likely

✔

✔

✔

✔

✔

allow 3 marks for 4 correct

allow 2 marks for 3 correct

allow 1 mark for 2 correct4

more than one tick in a row negates a mark

[8]

(a) Nucleus14

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(b) Type of cell Number of chromosomes

extra lines from left cancel the mark2

(c)

X X

X XX XX

Y XY XY

all three correct for 2 marks

one or two correct for 1 mark

allow XY or YX in correct places2

(d)

X X

X XX XX

Y

either circled1

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(e) 1 in 21

[7]

(a)

Characteristic Environmental Genetic Both

Eye colour ✔

A scar ✔

Weight ✔

3

5

(b) Key term Definition

extra lines from the left negate the mark2

(c)

Stage in selective breeding Order ofstage

Cows are bred over many generations 4

Parents are bred together 2

Cows with the desired characteristics arechosen

1

Calves with the most desired characteristicsare bred together

3

all 3 correct for 2 marks

1 or 2 correct for 1 markmax. 2

(d) beef / meat

allow hardiness, disease resistance1

milk yield1

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(e) higher veterinary costs1

less income from sale of (milk and meat) products1

[11]

(a) (i) (female) has XX / only X’s / no Y

allow has X chromosomes

ignore ref to genes / cells1

(ii) extra chromosome / has 47 chromosomes / one set has 3 copies

ignore reference to chromosome numbers other than 47 or no. 181

no. 181

6

(b) (i) 14

allow in range of 13.5 to 14.51

(ii) 7

allow in range of 6.75 to 7.25

accept ecf from 5bi1

(c) Advantages:any two from:• more than 1 embryo (so more chance of success)

allow method 2 may cause a miscarriage• tested at 3 days cf 10 weeks or tested earlier

tested when only 3 days old• tested before pregnancy• no termination / abortion• spare embryos have a potential use.

2

Disadvantages:any one from:• needs an operation

accept described hazard of operation• (spare) embryos / human life destroyed / harmed

must be comparative• high er cost• embryos might not implant / might not develop.

1

[8]

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(a) (i) any two from:• trapped / held (since sticky)• engulfed / covered by resin

allow engulfed / covered by amber• prevented decay.

2

7

(ii) any two from:• animal / plant (dies and) body covered in sediment / mud

ignore ref to rock

allow covered in tar / ice• bones / shells / hard parts do not decay• minerals enter bones / parts are replaced by other materials /

mineralisation• preserved traces / footprints / burrows / rootlet traces / impressions /

casts.2

(b) (i) New technology provides more valid evidence.1

(ii) any three from:examples of physical factors, e.g.

accept 3 physical factors or 3 biological factors or some of each forfull marks

• flooding• drought• ice age / temperature change.

ignore pollution

examples of biological factors, e.g.• (new) predators (allow hunters)• (new) disease / named pathogen• competition for food• competition for mates

competition must be qualified• cyclical nature of speciation• isolation• lack of habitat or habitat change.

if no other answers given allow natural disaster / weather change/ catastrophic event / environmental change / climate change for 1mark

3

[8]

(a) (i) (volume) increases (with time)

ignore numbers1

8

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(ii) there is more evidence / specimens / results (for Homo sapiens)

allow examples of this, eg more / better fossils

allow converse if clearly referring to Australopithecus

ignore reference to being ‘more recent’1

(b) 2.5 – 3.15 (million years ago)

accept any number in range1

(c) (i) Darwin1

(ii) any one from:

• they believed in other theories

allow they believed that God made all life• insufficient evidence

ignore ‘no evidence’• no proof

allow not enough proof• genes / mechanism of inheritance not known / discovered

1

[5]

(a) fossils show change over time.19

(b) covered in sediment / mud or sinks into the mud1

soft parts decay / are eatenorbones / hard parts / shell do not decay

1

minerals enter bones / parts are replaced by minerals / mineralisation

accept turns to rock

allow ‘is an impression’ / ‘imprint’ / ‘cast’1

(c) skin is soft / skin not preserved / not fossilised / skin decays

accept not enough / no evidence / no-one has seen one

allow ‘this fossil is only bones’1

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(d) any two examples of:

accept 2 physical factors or 2 biological factors or one of each forfull marks

physical factors such as volcanic activity (allow volcanoes) / earthquakes / asteroid(collision) / ice age / temperature change

ignore pollution

and / or

biological factors such as predators / disease / named pathogen / competition/ lack offood / mates / cyclical nature of speciation / isolation / lack of habitat or habitatchange

if no other answers given allow natural disaster / climate change /weather change / catastrophic event / environmental change for 1mark

2

[7]

(a) (i) fertilisation110

(ii) in sequence:

accept 1 next to gene, 2 next to chromosome and 3 next to nucleusin box

1 gene2 chromosome3 nucleus

allow 1 mark for smallest or largest in correct position2

(iii) DNA1

(b) (i) On diagram:

tick drawn next to X and / or Y from Parent 1

tick(s) must be totally outside grid squares

allow ticks around “parent ”

extra ticks elsewhere cancel1

(ii) 0.5 / ½ / 50% / 1:1 / 50:50 / 1 in 2

allow 2/4 / 2 in 4 / 2 out of 4 / ‘even(s)’ / ‘fifty – fifty’

do not allow 1:2 or ‘50 / 50’ or ‘50 – 50’1

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2 (out of 4) boxes are XX

or

half of the sperm contain an X-chromosome

allow XY is male and 2 (out of 4) boxes are XY1

[7]

(a) asexual reproduction111

(b) mitosis1

(c) clones1

(d) 441

[4]

(a) wolves112

(b) moose and wolves are on different scales1

(c) wolf population has increased so more moose are eaten

do not accept there are more wolves than moose1

(d) any two from:

• (other) predators

allow correct examples

allow ‘humans hunting moose’• (new) pathogens

allow diseases• competition

2

(e) any four from:

• variation (within species) of antler size

allow description relating to antlers• (caused by) different genes• as a result of sexual reproduction / process of meiosis / mutation• (phenotype) most suited to environment most likely to survive and breed

ignore natural selection unqualified• genes for large antlers (more likely to be) passed on to next generation

4

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reference to mate selectionorfightingorgaining territoryorcompetition for matesoravoiding predation

1

[10]

(a) Feature Function

extra lines from the left negate the mark2

13

(b) Contaminated food1

(c) any two from:

• cook food (thoroughly)• pasteurise food• wash hands properly• disinfect work surfaces• keep raw and cooked foods separate• only drink clean water

2

(d) It will not cause sickness and diarrhoea side effects1

(e) E1

B1

D1

[9]

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(a) organisms that reproduce together to form fertile offspring1

(b) (i) fossils of P and Q in same stratum / layer / level / height1

(ii) earlier − fossil in deeper layer / further down1

(iii) the fossils of animals S and T have many features in common, but T is morecomplex that S

1

the fossil of animal S was found in a deeper layer of rock than the fossil ofanimal T

1

14

(c) (i) X has white tail / shorter tail

allow other points eg X has furrier tail / smaller feet / is furrier

or

W has sharper claws / W has larger claws1

(ii) two (ancestral) populations separated / isolated (by geographical barrier / bycanyon / river)

1

genetic variation (in each population) / different alleles / different genotypes /(different) mutation(s)

1

different environmental conditions / example described

allow abiotic or biotic example1

the better adapted survive / natural selection occurs

allow survival of the fittestignore they adapt to the environment

1

so (different / favourable) alleles / genes passed on (in each population)1

eventually two types cannot interbreed successfully

allow to produce fertile offspring1

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(iii) any two from:• environments similar / described

allow example, e.g. similar predator(s) / food / climate• therefore similar adaptations / features / phenotypes suit

accept suitable named feature• original ancestor already well adapted

ignore reference to not enough time for evolution.2

[14]

(a) kills weeds among crops / does not kill crops1

(kills weeds) so less competition for named factor eg light / water / ions

ignore space1

crops grow better / higher yield1

15

(b) (i) plasmid1

(ii) use an enzyme

allow correct example1

(iii) only some cells become GM / take up the plasmid / take up resistance gene

allow idea of transfer of gene / plasmid to some plant cells frombacteria

1

GM cells survive / non-GM cells are killed1

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(c) Pro:(positive) correlation between use of glyphosate and number of cases of kidneydisease

allow 1 mark for justified conclusion that the claim is not justified1

+ any three from:Con:• lack of controls / control group• correlation does not prove a causal link• some other factor could be the cause

accept obesity / infection• no evidence that kidney patients actually consumed GM crops / crops treated

with glyphosate / no evidence about amount consumedor graph shows amount of herbicide not amount of GM crops grownor graph shows data only for maize and soya / not for other (GM) crops

• data have been manipulated by carefully chosen scales to make it look like theycoincide

• data from some years is missing• no data for the dosage of herbicide used

allow kidney disease has been around for much longer than GMcrops / better diagnosis of kidney disease.

3

[11]

(a) (i) in the chromosome(s)

ignore genes / alleles1

in the nucleus

allow nuclei

allow mitochondria1

(ii) the DNA / chromosomes / genes are replicated / copied / multiplied / doubled /duplicated

allow DNA is cloned

ignore same DNA / chromosomes / genes if unqualified1

16

(b) (i) 1 / one1

(ii) 2 / two1

(c) B1

[6]

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(a) any three from:

• parts of organisms have not decayed

accept in amber / resin

allow bones are preserved• conditions needed for decay are absent

accept appropriate examples, eg acidic in bogs / lack of oxygen• parts of the organism are replaced by other materials as they decay

accept mineralised• or other preserved traces of organisms, eg footprints, burrows and rootlet

traces

allow imprint or marking of organism3

17

(b) (i) teeth for biting (prey)

must give structure + explanation1

claws to grip (prey)

accept sensible uses1

wing / tail for flight to find (prey)1

(ii) any two from:

• new predators• new diseases• better competitors• catastrophe eg volcanic eruption, meteor• changes to environment over geological time

accept climate change

allow change in weather• prey dies out or lack of food

allow hunted to extinction2

[8]

(a) (different / alternative) forms of a gene

do not accept types of genes1

18

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(b) DNA isolated from embryo1

(fluorescent) probe mixed with embryo DNA1

probe (then) binds with embryo DNA1

(UV light) to show alleles / gene for disorder1

(c) genotypes of parents and gametes correct (Man D and d, Wife d and d)

allow half-size genetic diagram with only one d from wife1

offspring genotypes correct (½ = Dd and ½ = dd)

allow ecf if parental genotypes are wrong1

offspring phenotypes correctly assigned to genotypes1

(d) genotypes of parents and gametes correct (N and n)

allow ecf if parental genotypes are wrong1

offspring genotypes correct (NN, 2 × Nn, and nn)1

offspring phenotypes correctly assigned to genotypes;1

correct probability = 0.25 / ¼ / 25% / 1 in 4 / 1:3, only;

do not allow ‘3:1’ / ‘1:4’1

[12]

(a) (i) nucleus

correct spelling only

accept mitochondrion

ignore genes / genetic material / chromosomes1

19

(ii) base(s)

Accept all four correct names of bases

ignore nucleotides and refs to organic / N-containing1

(iii) 41

(iv) codes for sequence / order of amino acids

ignore references to characteristics1

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codes for a (specific) protein / enzyme

or

the sequence / order of three bases / compounds / letters

codes for a specific amino acid

or

the sequence / order of 3 bases / compounds / letters

codes for the order / sequence of amino acids1

(b) (i) DNA1

circular / a ring or a vector / described1

(ii) kills any cells not having kanr gene / so only cells with kanr gene survive1

hence surviving cells will also contain Bt gene / plasmid1

(iii) cells divide by mitosis

ignore ref to asexual reproduction

correct spelling only1

genetic information is copied / each cell receives a copy of (all) the gene(s) / allcells produced are genetically identical / form a clone

1

(iv) any two from:

• gene may be passed to pathogenic bacteria• cannot then kill these pathogens with kanamycin

orcannot treat disease with kanamycin

• may need to develop new antibiotics• gene may get into other organisms• outcome unpredictable

2

[13]

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(a) (i) alternative / different / one form of a gene

or

a mutation of a gene

do not allow a type of gene

(For info: CRAM = Childhood Recurrent Acute Myoglobinuria)1

20

(ii) not expressed if dominant / other allele is present or it is heterozygous

or

only expressed if dominant allele not present / no other allele present or it ishomozygous

need two copies to be expressed / not expressed if only one copy

allow ‘gene’ for allele1

(iii) unaffected parents have an affected child

allow 7 and 8 have 10

allow skips a generation1

(b) (i) has two alleles that are the same

accept (person is) nn / NN or has two recessive / dominant alleles1

(ii) (all) inherit N / normal / dominant allele from 1 / from father

ignore they are carriers1

all are Nn / none are nn / all are heterozygous1

(c) (i) genetic diagram including:

1 gametes correct or parental genotypes correct:

N and n + N and n or Nn + Nn

accept alternative symbols, if defined1

2 derivation of offspring genotypes: NN + Nn + Nn + nn

allow alternative if correct for parental gametes1

3 nn identified as CRAM

accept ¼ / 25% / 1 in 4 / 1 out of 4 / 1:31

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4 correct probability: 0.25

do not accept 3:1 / 1:41

(ii) any four points + conclusion:

pro PGD:

detected at earlier stage / at 3 days c.f. several weeks / before becomingpregnant

no / less chance of miscarriage c.f. CVS

does not involve abortion / less trauma / less pain / ethical comparison

higher chance of having unaffected child – eg ref to use of spare embryos

provides embryos for research4

pro CVS:

PGD may destroy some embryos

ethical implications of research on embryos (with PGD)

lower incidence of false positives / false results

low(er) financial cost

conclusion:

must relate to candidate’s argument

must have at least one point from each technique for max marks1

[15]

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b6 inheritance variation and name: evolution · 2018-03-27 · use evidence from the graphic above...

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