Unit 7 - genetics, population, evolution and ecosystems

Question 1

Pioneer species

Answer 1

First species to inhabit an area

Question 2

Primary succession

Answer 2

Where the land is completely bare

E.g. Following lava flow

Question 3

Secondary succession

Answer 3

Where some soil is already present, e.g. A ploughed field, or bush fire.

Question 4

Succession

Answer 4

The process by which a plant or animal community successively gives way to another until a stable climax is reached

Question 5

When a species colonises an area, how might they alter the environment?

Answer 5

• make it less for an existing species, causing competition with the existing one.
• make it more suitable for other species with different adaptations, as a relust this species may be out-competed by the better adapted new species.

Question 6

What features might a pioneer species have which makes they suit colonisation ?

Answer 6

• reproduce asexually, so can build the population quickly.
• produce large amounts of wind-dispersed seeds or spores, which can easily reach isolated situations.
• germinate seeds rapidly, so they don’t require a period of dormancy
• able to photosynthesise, as light is readily available but other food is not, so not dependent on animal species.
• the ability to fix nitrogen from the atmosphere due to few nutrients in the soil
• tolerance to extreme conditions

Question 7

Deciduous

Answer 7

Term applied to plants that shed all their leaves together at one season

Question 8

Climax community

Answer 8

When many species flourish and there is much biodiversity.

Question 9

Common features during succession

Answer 9

• Abiotic environment less hostile, this leads to
• a greater number and variety of habitats and niches, which produces
• increased biodiversity, this causes
• more complex food webs, leading to
• increased biomass

Question 10

Conservation

Answer 10

Active intervention by humans to maintain ecosystems and biodiversity.

Question 11

Main reasons for conservation

Answer 11

Personal
Ethical
Economic
Cultural and aesthetic

Question 12

Phenotype

Answer 12

The observable or biochemical characteristics of an organism.

Question 13

Genotype

Answer 13

Genetic constitution of an organism describing all alleles an organism has

Question 14

Codominant

Answer 14

When both alleles are expressed in the phenotype

Question 15

Genetic crosses

Answer 15

Method of representing parental gametes as well as finding out the offspring genotypes

Question 16

Dihybrid inheritance

Answer 16

Two characters determines by different genes located on different chromosomes are inherited in this way

Question 17

Sex linkage

Answer 17

Any gene carried on the x or Y chromosome

Question 18

Autosomal linkage

Answer 18

Two or more genes carried on the same autosome

Question 19

Epistasis

Answer 19

When one gene affects the expression of another

Question 20

Chi squared

Answer 20

Compares the difference between sets of observations and expected results

Question 21

Hardy weinberg

Answer 21

Equation used to estimate allelic frequency in a population subject to certain constraints

Question 22

Disruptive selection

Answer 22

Selection favouring the extreme phenotypes

Question 23

Allopatric speciation

Answer 23

Speciation where two populations become geographically separated

Question 24

Sympatric speciation

Answer 24

Speciation of a population within the same geographical location because of new factors introduced

Question 25

Niche

Answer 25

Describes how an organism fits into the environment

Question 26

Community

Answer 26

All the populations of different species living and interacting in a place at the same time

Question 27

Population

Answer 27

A group of individuals of one species that occupy the same habitat

Question 28

Ecosystem

Answer 28

Dynamic systems made up of a community and non-factors

Question 29

Succession

Answer 29

Describes the dynamic aspect of an ecosystem and how it changes over time

Question 30

Pioneer species

Answer 30

First species to colonise an inhospitable area

Question 31

Climax community

Answer 31

Final, stable point of succession. Wide range of biodiversity and consists of animals and plants.

Question 32

Mark, release, recapture method

Answer 32

Technique used to estimate population size within an ecosystem.
Compared the initial amount of marked organisms to those recaptured

Question 33

How do multiple alleles arise?

Answer 33

Mutations

Which are at different positions in a gene