BIOLOGY GRADUATION TEST REVIEW

Cells

What is biology?

• The study of living things• What is considered living?

–anything that has the ability to nourish, grow, and reproduce

–cells must be present

Cell Theory• The cell is considered the basic

unit of life.• All living things contain at least

one cell.• Cells come from pre-existing

cells.

Plant Cells versus Animal Cells ANIMAL CELL

PLANT CELL

Plant Cells versus Animal Cells

PLANT CELLS• cell wall (provides structure)• chloroplast (location of photosynthesis/

energy production)

ANIMAL CELLS• centrioles (responsible for cell reproduction)

Organelles Common to Both

STRUCTURE FUNCTION

nucleus control of all cell activities; location of DNA

mitochondria energy production

Golgi complex (apparatus)

assembles, sorts, and transports cell products

ribosome protein synthesis

chromosome composed of DNA containing genetic material

Cell Organelles, continued

STRUCTURE FUNCTION

cell membrane

phospholipid bilayer; maintains homeostasis; protects the cell

lysosome digests old cells and food (cleans up the cell)

endoplasmic reticulum

produces, stores, and transports protein (rough) and lipids (smooth)

flagella/cilia movement of materials

Prokaryotes“Pro-No”

• No true nucleus• No membrane-bound

organelles• No well-organized membrane

Prokaryotes“Pro-No”

• All prokaryotes are bacteria and all bacteria are prokaryotes

• Prokaryotes = bacteria (Monera)

Eukaryotes“Eu-True”

• True nucleus• Well organized membrane• Membrane – bound organelles

Eukaryotes“Eu-True”

• Most plants and animals and other specialized organisms

Active versus Passive Transport

ACTIVE TRANSPORT• requires energy (low concentration to high)• endocytosis and exocytosis• active transport (ATP is used)

PASSIVE TRANSPORT• diffusion (particles from high concentration to

low)• osmosis (water from high concentration to

low)• facilitated transport (diffusion using a

membrane protein)

Organic CompoundsORGANIC

COMPOUND DEFINITION FUNCTION

carbohydrates sugars and starches provide energy

lipids fats (insoluble in water) store energy

proteins amino acidsresponsible for

most cell functions

nucleic acids DNA and RNA store hereditary information

Homeostasis

• The maintenance of a constant, stable environment internally

•example: body temperature

Cell Membrane and Homeostasis

• utilizes active and passive transport

• diffusion and osmosis depends on environment (hydrophobic or hydrophilic)

Hydrophobic versus Hydrophilic

Hydrophobic• “water-fearing”• outside of cell

Hydrophilic• “water-loving”• inside of cell

GENETICS

Genetics

• The study of the inheritance of traits and how genes pass on these traits from parents to offspring

Important Genetic Vocabulary• trait: a characteristic of an organism

that is inherited (examples: eye color, hair type, etc.)

• gene: basic unit of heredity made of DNA that determines the characteristics of a trait

• allele: the two different versions of a gene for a particular trait (one received from each parent)

Genotype versus PhenotypeGENOTYPE

• an organism’s genetic makeup• includes the two alleles• represented with two letters (example: Bb)

PHENOTYPE• the physical appearance of a trait• expressed by the organisms genes• represented by description (example: brown

eyes)

Dominant versus RecessiveDOMINANT

• an allele that expresses itself while hiding the effects of another allele

• represented with a capital letter

• example: Bb (dominant brown eyes dominates over recessive blue)

RECESSIVE• An allele whose effects are hidden by a

dominant allele• Represented with a lower-case letter• example: Bb (dominant brown eyes dominates

over recessive blue)

Homozygous versus Heterozygous

HOMOZYGOUS• “homo-” means the

same• the pairing of alleles

that are the same• examples:

• BB is dominant homozygous brown

• bb is recessive homozygous blue

HETEROZYGOUS• “hetero-” means different• the pairing of unlike alleles• example:

• Bb is heterozygous brown

Gregor Mendel

• Father of Genetics• experimented with pea plants• established a method for

predicting how traits are inherited

Mendel’s Laws• The Law of Dominance: a recessive trait will

only be expressed when the organism’s genotype is recessive homozygous (bb)

• The Law of Segregation: during fertilization, new alleles are randomly formed; one can only predict offspring (using Punnett squares)

• The Law of Independent Assortment: each trait is inherited independently of other traits

Probability and Punnett Squares

• Probability is the likelihood an event will occur• Geneticists use Punnett squares to predict the

probability of genetic combinations• Example: When two heterozygous brown eyes

mate . . .

B b

B BB Bb

b Bb bb

Theory of Inheritance• Chromosomes are the physical basis of

inheritance (carry DNA).• Variability results from dominant and

recessive alleles.• The chromosomes in the male gamete and

female gamete join together during fertilization to form a zygote.

• gamete = sex cell• zygote = fertilized egg

DNA• deoxyribonucleic acid• found in chromosomes in the

nucleus• determines the hereditary traits of

an organism• contains all the information needed

for the production of proteins• protein sequences determine traits

RNA• ribose nucleic acid• aids in protein synthesis in the ribosome• 3 types:

• messenger RNA: mRNA carries the DNA nucleotide sequence for a protein from the nucleus to the ribosome

• transfer RNA: tRNA transports amino acids (building blocks of proteins) to the ribosome

• ribosomal RNA: rRNA makes up the structure of the ribosome

DNA replication• see figure 8-5 on p.149• self-duplication of the genetic material• results in two new DNA molecules• occurs during interphase (just before cell divides)• proteins unwind the DNA helix and each strand

acts as a template for a new strand• unbound nucleotides attach . . .

• A-T (adenine binds with thymine)• C-G (cytosine binds with guanine)

DNA transcription• to “transcribe” is to copy• mRNA is synthesized in the cell nucleus from

the DNA molecule• Just as in replication, the helix unwinds and

free nucleotides attach to make mRNA. . . • C-G (cytosine binds with guanine)• U-A (uracil binds with adenine)• Only DNA has thymine

• mRNA separates and moves out of the nucleus• DNA double helix reforms

DNA translation• process of translating the

genetic code to the amino acid sequence

• tRNA decodes the mRNA to read the DNA in order to make the correct protein

Mutations• A mutation is any change in the DNA

sequence.• A change in one nucleotide may

cause a change in the structure of the protein.

• During pregnancy, observing a karyotype (a chromosome picture) can detect chromosomal defects.

TAXONOMY

Taxonomy

• The study of the classification of organisms

Classification• Kingdom• Phylum• Class• Order• Family• Genus• Species

• King• Phillip• Cried • Out • For• Good• Soup

Binomial Nomenclature• Classification system used to give all organisms

a two-part name• First name = Genus name• Second name = Species name• Example:

– scientific name of a wolf is Canis lupus

KingdomsName

Pro- / Eu- karyote?

Uni- / Multi- cellular?

Examples

Monera prokaryote unicellular bacteria

Protista eukaryote unicellularalgae, seaweed,

protozoans, water molds

Fungi eukaryote multicellularyeasts, molds,

mildews, mushrooms, rust

Plantae eukaryote multicellular mosses, ferns, trees, shrubs, plants

Animalia eukaryote multicellularworms, insects, sponges, birds,

mammals

Kingdom Monera• bacteria• need water, nutrients, and a moderate

temperature to survive• autotrophs (make their own food) and

heterotrophs (obtain food from outside source)• decomposers (AKA saprophytes) = break down

dead organisms to release carbon and nitrogen• reproduce asexually (binary fission)• some possess flagella used for motion

Kingdom Protista• algae, seaweed, protozoans, water (slime)

molds• found in aquatic or damp environments• organisms that don’t fit in any other kingdom• autotrophs (algae) and heterotrophs

(protozoans)• reproduce either asexually or sexually• some have flagella or cilia for motion• gave rise to all other eukaryotic organisms

Kingdom Fungi• mushrooms, yeast, molds, mildews, rusts• all are heterotrophs (do not contain

chlorophyll)• absorb food from environment• many are saprophytes (decomposers) that

obtain nutrients from dead or decaying plants and animals

• reproduce either asexually or sexually

Kingdom Plantae• autotrophs (utilize photosynthesis)• Two groups:

– bryophytes (nonvascular) have no roots, stems, or leaves and transport nutrients using diffusion (examples: mosses, liverworts, hornworts)

– tracheophytes (vascular) have roots, stems, and leaves that transport water and nutrients throughout the plant (examples: ferns, gymnosperms, and angiosperms)

• all reproduce both sexually and asexually (alternation of generations)

Kingdom Animalia• worms, insects, sponges, birds, mammals• all are heterotrophs that have a digestive

cavity in which food is digested and absorbed• all reproduce sexually, but some (like jellyfish)

can also reproduce asexually

Unicellular versus Multicellular

UNICELLULAR• single-celled• composed of one cell• all bacteria and protists• non-specialized cells

MULTICELLULAR• multi-celled• composed of many cells• all other organisms (fungi, plants, & animals)• cells are specialized to perform different

functions

Asexual Reproduction• involves only one parent• no specialized sex cells are produced• does not undergo meiosis• chromosomes are duplicated in mitosis• Examples:

– binary fission = cell simply splits– budding = offspring grows out of the side of the

parent

Sexual Reproduction• involves two parents so genetic diversity is

increased• specialized male and female sex cells

(gametes) are produced • gametes fuse during fertilization to produce a

zygote (fertilized egg)• gametes are formed in meiosis• chromosomes are duplicated in mitosis

Haploid versus Diploid

HAPLOID• sex cells• contain one of each chromosome• human haploid cells have 23

chromosomes

DIPLOID• all non-sex cells• contain 2 copies of each chromosome• human diploid number is 46 (two sets of

23 – a set from each parent)

Mitosis• begins after interphase = cell growth,

chromosome (DNA)replication, and prep for division (most of a cell’s life cycle is spent in interphase)

• results in two identical daughter cells containing same number of chromosomes and genetic information as the parent cell

Phases of Mitosis1. Prophase = chromosomes become visible

(present), nucleus membrane disappears, and in animal cells, centrioles move to opposite sides of the cell

2. Metaphase = chromosomes line up in the middle of the cell

3. Anaphase = chromosomes move toward opposite poles of the cell (move away)

4. Telophase = chromosome become less distinct and nucleus membrane reappears; nucleus divides into two

Cytokinesis• occurs after telophase• cytoplasm divides forming two

separate cells

Meiosis• cell division that results in the formation

of haploid gamete cells (sex cells)• Meiosis I

– reduction division– diploid cell divides creating two haploid

cells• Meiosis II

– two haploid cells from meiosis I divide resulting in 4 haploid daughter cells

Mitosis versus Meiosis

MITOSIS• resulting cells have same number and kind of

chromosomes as parent cell• used for cell growth, tissue repair, and asexual

reproduction

MEIOSIS• resulting cells have half the number of

chromosomes as parent cell• used for gamete formation

ECOLOGY

Biomes

• Biome = a large area characterized by a certain climate and types of plants and animals

• 6 major biomes on Earth

Biome CharacteristicsName Characteristics

Tundra permanently frozen subsoil

Taigalong severe winters;

summers with thawing subsoil

Temperate Forest moderate precipitation; cold winters; warm summers

Tropical Forest heavy rainfall; constant warmth

Grassland variability in rainfall and temperature; strong winds

Desert sparse rainfall; extreme daily temperature fluctuations

Biomes of the Earth

Ecosystem Vocabulary

• Ecosystem = a part of the environment with its organisms, their interactions, and the physical and chemical factors that affect them

• Community = populations of different species that interact in an ecosystem

• Population = all the individuals of the same species living in a community

Members of an Ecosystem

• Producers = organisms that can make their own food; autotrophs; examples: bacteria, protists, plants

• Consumers = organisms that eat other organisms to get energy; heterotrophs; examples: fungi and animals

Consumer Classification• Herbivore = primary consumer who only eats plants;

example: cow• Carnivore = secondary consumer who only eats

other animals; examples: shark and tiger• Omnivore = consumer that eats both plants and

animals; example: most humans• Scavengers = animals that find dead plants or

animals and eat them; examples: flies, wasps, cockroaches, earthworms

• Decomposers = break down dead organisms to receive energy; examples: fungi and bacteria

Predator versus Prey• All animals must eat to survive. Animals can

be either predators or prey.• Predators hunt prey.• With predators always on the lookout for a

meal, prey must constantly avoid being eaten. • Any adaptation the prey uses adds to the

chances of survival for the species.• Some adaptations are defense mechanisms

which can give the prey an advantage against enemies.

Survival Defense Mechanisms• speed

– You can’t eat what you can’t catch!• physical or chemical features

– physical examples: quills on a porcupine or hard shell of a turtle

– chemical examples: stink of a skunk; poisons of a dart frog

• camouflage – allows the animal to blend in with its environment

to avoid being detected– used by both predators and prey

Parasite versus Host

• A parasite is an animal or plant that lives in or on a host (another animal or plant)

• Parasites obtain nourishment from the host without benefiting or killing the host

• Examples: canine heartworms, malaria, hookworms, pinworms, tapeworm

Food Chain• a diagram that shows

the way energy is transferred from one organism to another

• each step in a food chain is called a trophic level

• begins with producers and ends with decomposers

Food Web

• complex, interconnecting food chains in a community

• more accurate than food chain

Pyramids of Biomass/Energy