Topic 7: Key words and concepts

Question 1

genotype

Answer 1

genetic make-up of an organism

Question 2

phenotype

Answer 2

observable characteristics of an organism

Question 3

gene

Answer 3

sequence of nucleotide bases that code for a polypeptide

Question 4

locus

Answer 4

the position of a particular gene on a DNA molecule

Question 5

dominant

Answer 5

Allele that’s always expressed

Question 6

recessive

Answer 6

both alleles needed for it to be expressed

Question 7

codominance

Answer 7

both alleles are expressed in the phenotype when present

Question 8

dihybrid inheritance

Answer 8

two different genes located on two different chromosomes

Question 9

multiple alleles

Answer 9

where there are more than two alleles of which only two may be present at the loci of an individual’s homologous chromosomes

Question 10

sex-linage

Answer 10

a gene that’s carried on the X or Y chromosome

Question 11

autosomal linkage

Answer 11

when two or more genes are carried closely together on the same chromosome

Question 12

chi-squared formula

Answer 12

∑ (observed # - expected #)² / expected #

Question 13

population

Answer 13

group of organism of the same species occupying a particular space at a time

Question 14

gene pool

Answer 14

all the alleles of all the genes of individuals in the population

Question 15

hardy-weinberg

Answer 15

p² + 2pq + q² = 1

Question 16

hardy-weinberg assumes:

Answer 16

• no mutation
• mo migration or immigration
• large sample
• Random mating
• no flow of genes
• no natural selection

Question 17

factors affecting variation

Answer 17

• mutations
• meiosis - independent assortment and crossing over
• random fertilisation

Question 18

speciation

Answer 18

evolution of new species from existing ones

Question 19

allopatric speciation

Answer 19

geographically separated leading to reproductive isolation

Question 20

sympatric speciation

Answer 20

species become reproductively isolated - due to mutation