Topic 7 -

Question 1

Phenotype

Answer 1

The expression of genes and its interaction with the environment

Question 2

Co dominant

Answer 2

Both alleles are equally dominant and expressed in the phenotype

Question 3

Sex linkage

Answer 3

A gene whose locus is on the X chromosome

Question 4

Autosomal linkage

Answer 4

Genes that are located on the same chromosome (not sex chromosomes) . This reduces amount of possible gametes because if ‘R’ and ‘Y’ allele (both dominant) are in the same chromosomes, then we can we cannot get Ry gamete as R is linked to Y allele.

IF THERES MORE THAN 2 PHENOTYPES IN THE QUESTION, IT IS DIHYBRID CROSS

Question 5

Epistasis

Answer 5

When one gene modifies or masks the expression of another gene at a different locus (This is a dihybrid cross)

IF THERES MORE THAN 2 PHENOTYPES IN THE QUESTION, IT IS A DIHYBRID CROSS

Question 6

Monohybrid

Answer 6

The inheritance of a single gene

Question 7

Dihybrid

Answer 7

The inheritance of 2 genes ( WE GET 4 POSSIBLE GAMETES FROM EACH PARENT, IF PARENT HAS GENOTYPE AaBB , we cross the gametes AB, AB, aB, aB - Each ‘a’ is paired with each ‘b’ gene)

IF THERES MORE THAN 2 PHENOTYPES IN THE QUESTION, IT IS DIHYBRID

Question 8

Genotype

Answer 8

The genetic constitution of an organism

Question 9

Homozygous

Answer 9

A pair of homologous chromosomes carrying the same alleles for a single gene

Question 10

Heterozygous

Answer 10

A pair of homologue chromosomes carrying different alleles first a single gene

Question 11

Recessive allele

Answer 11

An allele which is only expressed if no dominant allele present

Question 12

Dominant allele

Answer 12

An allele that will always be expressed in the phenotype

Question 13

What is the expected ratio for dihybrid cross of 2 heterozygous parents

Answer 13

9:3:3:1

Question 14

What can crossing over impact autosomal linkage

Answer 14

It can create new combinations of gametes, so if ‘R’ and ‘Y’ is linked, it can form a gamete with ‘R’ and ‘y’

Question 15

Population

Answer 15

All individuals of one species in one area at one time that can interbreed to make fertile offspring

Question 16

Gene pool

Answer 16

All the alleles of all the genes within a population at one time

Question 17

Allele frequency

Answer 17

The proportion of an allele within a gene pool

Question 18

3 factors that cause natural selection

Answer 18

Predation, disease and competition

Question 19

Genetic drift

Answer 19

The change in allele frequency within a population between generations

Question 20

Habitat

Answer 20

Part of an ecosystem in which a particular organism lives

Question 21

Community

Answer 21

All the populations of different species in the same area at the same time

Question 22

Ecosystem

Answer 22

A community and the abiotic and biotic components of an environment

Question 23

Niche

Answer 23

An organisms role within an ecosystem and its habitat

Question 24

Carrying capacity

Answer 24

The maximum population size an ecosystem can support

Question 25

Bioptic factors

Answer 25

Impact of the interactions between organisms

Question 26

Explain the mark-release-recapture method

Answer 26

1) Initial sample of the population is captured 2) Individuals are then marked 3) Marked individuals are released, long enough to randomly disperse (Catch, mark, release) 4) A second sample is captured 5) Record total number in second sample and number recaptured (ones marked) 6) Estimate population size by (first sample X second sample)/(number recaptured)

Question 27

Sample using a quadrat

Answer 27

1) Create a gridded area using tape measures 2) Use random number generator to generate random coordinates 3) Place quadrat at each coordinate (calculate density/percentage cover/frequency) 4) Repeat at least 30 times and calculate a mean 5)

Question 28

Sample using a line transect (for shoreline)

Answer 28

1) Place tape measure at à right angle to the shore line 2) Place quadrat every 5 metres 3) Calculate data (local frequency/density/percentage cover ) 4) Repeat at least 30 times by placing another 30 transects along the beach at right angles to the shore line (MUST SPECIFY HOW YOUR GOING TO REPEAT BY DESCRIBING POSITION OF THE TRANSECT)

Question 30

Considerations for mark release recapture

Answer 30

How they are captured and marked must leave no permanent harm .Mark must be non-toxic .Mark must not increase chance of predation .Mark must not reduce chance of reproduction

Question 31

Assumptions made with mark release recapture

Answer 31

.The population size is constant (no birth/death and no migration) .Animals always redistribute evenly (whereas they usually huddle around food)

Question 32

Pioneer species

Answer 32

Adapted to live in harsh abiotic factors, through death and decomposition they make abiotic factors less hostile