Unit 3

Homework

Biodiversity and the Distribution of Life Homework 1

1. Marsh marigold is a waterside plant which grows beside burns.

The abundance of marsh marigolds was estimated in five sampling areas

beside a burn in the Scottish borders. Average values of three abiotic

factors were also calculated for each area.

The results are shown in the table below:

(a) What is meant by the term „abiotic factor‟?

______________________________________________________

____________________________________________________(1)

(b) Name one abiotic factor which does not affect the abundance of marsh

marigolds.

_____________________________________________________(1)

(c) What is the relationship between Average soil nitrate concentration

(ppm) and Abundance on marsh marigold?

______________________________________________________

______________________________________________________

____________________________________________________(1)

2. Read the passage below and use the information to answer the questions

which follow. (Adapted from Hostile Habitats, Scottish Mountaineering

Trust, 2006).

As you climb a mountain or hill, the vegetation gradually changes. In Scotland, trees and tall grasses in the glens are replaced on the mountain tops by lichens and dwarf mosses less than a centimetre high. The treeline is the maximum altitude at which trees can grow. Scottish hills have relatively little tree cover and so the treeline is not always obvious but it does form a real ecological boundary. If trees had not been cleared by humans in past centuries, the slopes below the treeline would be covered in forest. Low growing vegetation is dominant on the higher slopes. The factors which produce the treeline are not clearly understood but the average temperature during the growing season seems to be important. Under colder conditions, trees are at a disadvantage compared to low growing, denser vegetation. The growing tips of trees are fully exposed to high winds which cause physical damage and slow down growth of shoots by drying them out. High winds in wet conditions cause wind chill which can further damage shoots. In the case of low growing plants, these effects are reduced as their growing shoots are protected by the surrounding vegetation. The treeline in Scotland is generally lower than in other countries a similar distance from the equator. The exact height of the treeline varies across Scotland. The wet and windy conditions in the west of Scotland produce a treeline between 200 m and 450 m above sea level. In the east of Scotland, the treeline is between 500 m and 650 m above sea level. Other types of vegetation show similar effects, with mountain plants being found at lower levels on the west coast.

(a) Give two types of plants you might expect to find growing on mountain

tops in Scotland.

1 ___________________________________________________

2 _________________________________________________(1)

(b) Most hills in Scotland do not have woodland present up to the potential

treeline. Why is this?

____________________________________________________

____________________________________________________

__________________________________________________(1)

(c) According to the passage, what factor might be important in

determining how high up a hill trees can grow?

____________________________________________________

__________________________________________________(1)

(d) What two factors are needed to produce wind-chill?

1 ___________________________________________________

2 _________________________________________________(1)

(e) The passage states that, “Low growing vegetation is dominant on the

higher slopes”. What advantage does this type of vegetation have

which allows it to grow at higher altitudes than trees?

____________________________________________________

____________________________________________________

__________________________________________________(1)

(f) What is the average range of the height of the treeline across the

whole of Scotland?

From ________________ to ______________ m above sea level (1)

(g) In summer, red deer migrate to graze above the treeline. In which

part of Scotland would they have to go higher to do this?

____________________________________________________

__________________________________________________(1)

Biodiversity and the Distribution of Life Homework 2

1. The picture below shows the distribution of one biome across earth.

(a) What is meant by the term biome?

1

(b) Which biome is shown in the map above?

1

(c) In Scotland we live in a decidous forest biome.

The table below shows the average monthly rainfall in Scotland over the course of six

months.

1

(d) Present this information as a bar graph by:

(i) adding a suitable scale to both axis; 1

(ii) adding labels to both axis; 1

(iii) plotting the graph 1

2. Use words from the list to complete the following sentences.

List population community habitat

A pond provides a ________________ for a _____________________ of many

different types of organisms.

Plants of the same species form a ______________________ . 1

3. What term is used to describe the role that an organism plays within its community?

1

4. A study has shown that Scotland‟s river otter population is increasing after falling

sharply over the last 40 years.

Otters live along the banks of rivers, usually in reeds and gaps between tree roots.

Fish are their main food.

(a) What term is used for the place where otters live?

1

(b) What disadvantage might otters have if reeds are removed from riverbanks?

1

Energy in Ecosystems Homework 1

1. The diagram below shows the transfer of energy through a food chain in

a wood. The numbers represent the units of energy in the different

populations of the food chain.

a. Complete the table below using information from the diagram:

Population Energy Content (units)

Caterpillar

480

Hawk

(2)

b. 4% of the light energy reaching the oak tree is converted into new

plant material. How much energy did the oak tree receive?

Space for calculation

_______________ units

(1)

2. A pyramid of biomass, including mussels, is shown below:

a. Explain what is meant by a pyramid of biomass

_______________________________________________________

_______________________________________________________

_____________________________________________________(1)

b. In an investigation, mussels were found to eat an average of 600 g of

plankton per day. This plankton contains 450 g of water. The dry weight

of the plankton contains 20% protein.

Calculate how much protein a mussel eats per day.

Space for calculation

___________ g (1)

c. A different food chain from the ocean is shown below:

Plankton krill blue whale

Which population in the food chain contains the least energy?

_________________ (1)

3. The diagram shows some of the stages in the nitrogen cycle:

a. Complete the table by giving a number from the diagram to match each

of the named stages:

Stage Number

Absorption

Death

Nitrification

Decomposition

(2)

b. Name chemical X

________________________ (1)

c. Name the type of organism responsible for stage 3

________________________ (1)

d. Name three uses of Nitrogen by the plant

_____________________________________________________(1)

Energy in Ecosystems Homework 2

Extended Response Questions

1. The pictures below show a food chain which is also represented by two

types of pyramid.

Name the type of pyramid X. Explain why both pyramids are correct for

this food chain.

(5)

2. Write notes on how animals can reduce intraspecific competition using

the following methods:

i. co-operative hunting (1)

ii. dominance hierarchy (2)

iii. territorial behaviour (2)

(5)

Sampling Techniques Homework 1

1. Three groups of students used quadrats to carry out a survey on the

distribution of mussels on different areas of a shore.

Each quadrat measured 50 cm × 50 cm. (Four quadrats = 1 m2).

The positions of the quadrats and the number of mussels found is shown below

for each group.

(a) Complete the following table with the results from group C.

Space for calculation.

1

(b) Which group has made an error in their sampling technique which makes their

results less reliable than other groups?

State the error this group has made and describe an improvement which would

increase the reliability of their results.

Group ___________

Error _____________________________________________________ 1

Improvement _______________________________________________ 1

2. Marsh marigold is a waterside plant that grows beside burns.

The abundance of marsh marigolds was estimated in five sampling areas beside

a burn in the Scottish borders. Average values of three abiotic factors were

also calculated for each area.

The results are shown in the table below.

(a) Name one abiotic factor which does not affect the abundance of marsh

marigolds.

1

(b) The soil pH for each sampling area was measured using a pH meter with a

probe which was pushed into the soil to obtain each reading.

(i) Identify a possible source of error in measuring a named abiotic factor

and suggest how to minimise it.

Abiotic Factor ___________________

Source of error ___________________

How to minimise it ____________________________________________

__________________________________________________________ 2

(ii) How was the measurement of the abiotic factors in the survey carried out to

reduce the effect of atypical results?

1

3. Two groups of pupils set pitfall traps in the school gardens to sample

invertebrates living there.

The diagrams below show the invertebrates collected by the pupils.

(a) Complete the following key using information from the diagrams.

2

(b) Give two features of the beetle mentioned in the key.

___________________

___________________ 1

1.

Adaptation, natural selection and evolution

Homework 1

In African grasslands impala, giraffe and zebra feed on Acacia trees. Impala

and zebra also graze on grasses.

(a) State one way that competition for food is reduced between zebras and

giraffes.

1

(b) The Acacia tree is adapted to withstand long periods of drought.

Suggest an adaptation the Acacia tree may show that allows it to survive long,

dry periods.

1

2 Charles Darwin visited the Galapagos Islands. He found different species of

finch on the different islands.

The following gives information on the size and shape of beaks and the island

habitats of two of the Galapagos finches.

Size and shape of beak Habitat

Long and narrow Rotting logs that provide food for insects

Short and wide Trees and shrubs that provide seeds and nuts

(a) State which finch eats insects and give a reason for your answer.

__________________________________________________________ 1

(b) Identify two ways in which competition between finch A and finch B is

reduced.

1

3. Down‟s Syndrome is an example of a condition caused by a change to the

chromosomes.

(a) What is the correct term for a change to the chromosomes? 1

____________________

(b) The following table shows the risk to women of different ages of having a

baby with Down‟s Syndrome.

1

How many times greater is the risk to a 42 year old woman of having a Down‟s

Syndrome baby, compared to an 18 year old woman?

Space for calculation.

_________ times greater 1

(c) Complete the line graph below by:

1 completing the scale on the y-axis; 1

2 adding a label to the y-axis; 1

3 plotting the graph. 1

4. Mutation rate can be increased artificially using chemical agents.

Give another example of a mutagenic agent.

___________________________ 1

Adaptation, natural selection and evolution – Extended

Response Questions

The diagram below shows the two different forms of the peppered moth Biston

betularia on the bark of a tree located in an unpolluted area.

Name and describe the process by which the black form of the moth became the

most common form in polluted areas of Scotland.

5

Give an account of the importance of isolating mechanisms, mutations and natural

selection in the evolution of new species.

5

Human Impact on the Environment Homework 1

1. The bar chart shows the average annual losses in yield caused by insects

and disease in the production of three crops in Scotland.

a) Which crop has the lowest combined percentage loss from these two

causes?

_______________________________________________________

_______ (1)

b) The total crop of oats harvested was 130 000 tonnes. Calculate the yield

of oats which would have been produced if insects and disease had not

affected the plants.

_____________ (1)

c) Explain why it would not be a valid conclusion to say that disease caused

more tonnes of oats to be lost than any other of the crops named.

_______________________________________________________

_______ (1)

d) Oilseed rape is a common crop which has average annual losses of 9% to

insects and 12% to disease.

Use this information to complete the bar chart by adding labels and bars

in the space provided.

(1)

2. Read the following passage and answer the questions based on it.

Adapted from GM Organisms by John Pickrell, www.newscientist.com

Genetic modification (GM) of crops began with the discovery that the soil

bacterium Agrobacterium could be used to transfer useful genes from unrelated

species into plants. The Bt gene is one of the most commonly inserted. It

produces a pesticide toxin that is harmless to humans but is capable of killing

insect pests. Many new crop types have been produced. Most of these are

modified to be pest, disease or weedkiller resistant, and include wheat, maize,

oilseed rape, potatoes, peanuts, tomatoes, peas, sweet peppers, lettuce and

onions.

Supporters argue that drought resistant or salt resistant varieties can flourish

in poor conditions. Insect-repelling crops protect the environment by minimising

pesticide use. Golden rice with extra vitamin A or protein-enhanced potatoes

can improve nutrition.

Critics fear that GM foods could have unforeseen effects. Toxic proteins might

be produced or antibiotic-resistance genes may be transferred to human gut

bacteria. Modified crops could become weedkiller resistant “superweeds”.

Modified crops could also accidentally breed with wild plants or other crops.

This could be serious if, for example, the crops which had been modified to

produce medicines bred with food crops.

Investigations have shown that accidental gene transfer does occur. One study

showed that modified pollen from GM plants was carried by the wind for tens of

kilometres. Another study proved that genes have spread from the USA to

Mexico.

a) What role does the bacterium Agrobacterium play in the genetic

modification of crops?

_______________________________________________________

_______________________________________________________

________________ (1)

b) Crops can be genetically modified to make them resistant to pests,

diseases and weedkillers. Give another example of genetic modification

that has been applied to potatoes.

_______________________________________________________

_______________________________________________________

________________ (1)

c) Explain why a plant, which is modified to be weedkiller resistant could be:

i. Useful to farmers

__________________________________________________

__________________________________________________

________________ (1)

ii. A problem for farmers

__________________________________________________

__________________________________________________

________________ (1)

d) Give one example of a potential threat to health by the use of GM crops.

_______________________________________________________

_______________________________________________________

________________ (1)

e) What is your opinion on GM crops? Give at least one reason for your

answer.

_______________________________________________________

_______________________________________________________

_______________________________________________________

_______________________________________________________

__________________________________ (1)

Human Impact on the Environment Homework 2

1. When greenfly feed on cotton plants, they release a sticky mixture of

sugars onto the leaves. This causes problems in the cotton industry.

Researchers tested three wild yeasts to find a strain which could digest

and remove the sugars without harming the cotton plants.

The results are shown on the chart below.

a) Which sugar was completely digested by all the strains of yeast?

________________________ 1

b) By comparing the results of all three strains of yeast, which sugar

was the least well digested?

________________________ 1

c) Which strain of yeast would be the most useful in solving the

problem caused by the greenfly?

Give a reason for your answer.

Strain __________

Reason ___________________________________________________ 1

2. Read the following passage and answer the questions based on it.

Adapted from GM Organisms by John Pickrell, www.newscientist.com

Genetic modification (GM) of crops began with the discovery that the soil

bacterium Agrobacterium could be used to transfer useful genes from

unrelated species into plants. The Bt gene is one of the most commonly

inserted. It produces a pesticide toxin that is harmless to humans but is

capable of killing insect pests. Many new crop types have been produced.

Most of these are modified to be pest, disease or weedkiller resistant, and

include wheat, maize, oilseed rape, potatoes, peanuts, tomatoes, peas, sweet

peppers, lettuce and onions.

Supporters argue that drought resistant or salt resistant varieties can

flourish in poor conditions. Insect-repelling crops protect the environment by

minimising pesticide use. Golden rice with extra vitamin A or

protein-enhanced potatoes can improve nutrition.

Critics fear that GM foods could have unforeseen effects. Toxic proteins

might be produced or antibiotic-resistance genes may be transferred to

human gut bacteria. Modified crops could become weedkiller resistant

“superweeds”. Modified crops could also accidentally breed with wild

plants or other crops. This could be serious if, for example, the crops which

had been modified to produce medicines bred with food crops.

Investigations have shown that accidental gene transfer does occur. One

study showed that modified pollen from GM plants was carried by the wind

for tens of kilometres. Another study proved that genes have spread from

the USA to Mexico.

a) What role does the bacterium Agrobacterium play in the genetic

modification of crops?

1

b) Crops can be genetically modified to make them resistant to pests, diseases

and weedkillers. Give another example of genetic modification that has been

applied to potatoes.

1

c) Explain why a plant, which is modified to be weedkiller resistant could

be:

useful to farmers.

1

a problem for farmers.

1

3. Environmental protection analysis was carried out on water samples

from three burns.

The Mains Burn had the highest pH at 8.0. It also had the highest oxygen

saturation at 94% compared to Bell‟s Burn which had the lowest at 65%.

The Hatchery Burn had the lowest value for suspended solids at 4.0 mg/l, with

an oxygen saturation of 91.5%.

Bell‟s Burn had a suspended solids reading of 5.6 mg/l and the lowest pH at 7.7

compared to a value of 7.9 for the Hatchery Burn. The highest reading for

suspended solids was recorded in the Mains Burn with a value of 6.0 mg/l.

Complete the following table with the data in the passage using suitable column

headings.

3