REVISION

Question 1

Define variation

Answer 1

the range of phenotypes in an offspring. This due to a variation in genes

Question 2

What are the three types of variations?

Answer 2

1. Mutations
2. Independent assortment: different combinations of chromosomes
3. Recombination or crossover

Question 3

What is natural selection?

Answer 3

Individuals with certain characteristics are better adapted to a particular environment and thus survive to pass on these genes

Question 4

What are selection agents?

Answer 4

Abiotic or biotic factors that influence survival

Question 5

Define evolution

Answer 5

change over time into a different species

Question 6

Define a species

Answer 6

A group of closely related organisms that are very similar to each other and are capable of interbreeding and producing fertile offspring

Question 7

List some Biotic factors:

Answer 7

Predators, disease, competition, availability of food

Question 8

List some abiotic factors:

Answer 8

heat, cold, wind, availability of oxygen and water, pH of soil and water, living space

Question 9

List the four main pieces of evidence for support of evolution and briefly explain them:

Answer 9

1. Fossil evidence: fossils found that look like organisms that live today
2. Biogeography: distribution of animals and the concentration of similar types of animals in certain places on earth
3. Comparing embryos: similarities between different animals embryos is observed. Particularly evident in vertebras.
4. Comparative DNA: chimps and humans share 96.2% of their DNA which supports that they have a common ancestor

Question 10

Define convergent evolution:

Answer 10

Different animals from different evolutionary paths that have similar features due to adaptions to a similar environment. for example sharks and dolphins.

Question 11

Define divergent evolution:

Answer 11

Physical features of a common ancestor change overtime to perform different functions in different environments

Question 12

Define analogous structures:

Answer 12

Body parts that do the same job, however, are made up of different parts

Question 13

Define Homologous structures:

Answer 13

Body parts made of the same thing or from a common ancestor, however, do a completely different job or have a different function

Question 14

Define Reproductive Isolation:

Answer 14

When species are isolated by barriers which prevent interbreeding

Question 15

List and define some Prezygotic Isolation Mechanisms:

Answer 15

1. Physical Barriers: mountains, rivers, oceans, ice sheets, deserts
2. Temporal Barriers: mating seasons, nocturnal
3. Habitat Barriers: ground or tree-dwelling, forest or grasslands
4. Behavioural: mating calls, rituals, dances and body language displays, courtship rituals
5. Gamete morality: sperm not being able to survive in the reproductive tract of another species
6. Structural barriers: shape and size of mating organs

Question 16

List and define some Postzygotic Isolation Mechanisms:

Answer 16

1. Hybrid Sterility: offspring produced is sterile
2. Hybrid Inviability: offspring produced is not viable in womb and dies while mother is pregnant
3. Hybrid Breakdown: Second generation of hybrid offspring infertile or inviable
4. Hybrid Availability: lack of fellow hybrids to continue reproduction

Question 17

List differences between primates and humans:

Answer 17

• cognition and thought
• amount of hair
• bipedalism
• speech
• chin bone
• canine teeth size
• S-shape or C-shape spine
• Opposable big toe
• the ratio of legs to arms

Question 18

Define Hominid:

Answer 18

the group consisting of all modern and extinct great apes.

Question 19

Define Hominin:

Answer 19

the group consisting of all modern and extinct human species and all immediate ancestors of human

Question 20

Outline the basis of the Multiregional Hypothesis for Human evolution:

Answer 20

Human ancestors left Africa and the modern Homo sapiens emerged gradually throughout the world and as the populations dispersed they remained in ‘genetic contact’

Question 21

Outline the basis of the Replacement Hypothesis for Human evolution:

Answer 21

Also known as the ‘Out of Africa Hypothesis’. Homo sapiens developed as a separate species in Africa, then these completely modern humans spread around the globe, replacing the archaic populations (Neanderthals) when they came in contact

Question 22

Define Race

Answer 22

A subdivision of a species where gene flow is possible

Question 23

Define Allopatric evolution

Answer 23

Different houses in different areas to live in

Question 24

Define Sympatric evolution

Answer 24

Same houses in same areas to live in

Question 25

What type of evolution is the Replacement Hypothesis?

Answer 25

Sympatric

Question 26

What type of evolution is the Multiregional Hypothesis?

Answer 26

Allopatric

Question 27

Give the three main defining facts about human races:

Answer 27

1. 3 main human races
2. African/negroid, caucasian, mongoloid
3. Based on shared physical traits