Chapter 9 - Genetic Diversity

Question 1

What is a homologous pair?

Answer 1

One paternal and one maternal chromosome, same genes present but different alleles

Question 2

What are gametes?

Answer 2

Haploid sex cells

Question 3

What is a haploid cell?

Answer 3

a cell with a single set of unpaired chromosomes

Question 4

What is a diploid cell?

Answer 4

a cell with a complete set of chromosomes

Question 5

What is fertilisation?

Answer 5

the fusion of two gametes to form a zygote

Question 6

Describe Meiosis

Answer 6

2 divisions to make 4 daughter cells daughter cells are genetically different makes gametes

Question 7

Describe Mitosis

Answer 7

1 division 2 daughter cells genetically identical daughter cells for growth and repair

Question 8

Define gene mutation

Answer 8

a change in the base sequence of DNA substitution and deletion eg) substitution and deletion

Question 9

How could a mutation cause a non functioning protein?

Answer 9

Change to triplet during replication alters mRNA codon different anticodon —-> different amino acid changes primary structure alters hydrogen/ionic bonding in the tertiary structure

Question 10

How could a mutation not result in a non functioning protein?

Answer 10

DNA is degenerate so a change to a base may not alter primary structure no change to bonding in tertiary structure

Question 11

What is chromosome non-dysfunction?

Answer 11

Chromosomes don’t separate properly during either MI or MII eg) causes downs syndrome

Question 12

What happens at Prophase?

Answer 12

chromosomes condense and become visible, nuclear membrane breaks down

Question 13

What happens at Metaphase?

Answer 13

The homologous pairs line up, spindle forms and attaches to centromere

Question 14

What happens at Anaphase?

Answer 14

homologous pairs pulled to poles

Question 15

What happens at Telophase?

Answer 15

nuclei reform and the cell divides

Question 16

Describe directional selection

Answer 16

extreme is selected for eg) antibiotic resistance

Question 17

describe how directional selection may come about

Answer 17

change in environmental conditions individuals with extreme characteristics are more likely to survive and reproduce increasing the presence of characteristic in offspring

Question 18

describe stabilising selection

Answer 18

mean is selected for, making normal distribution more clustered around the mean

Question 19

define genetic diversity

Answer 19

the number of alleles of a gene in a pop

Question 20

what is natural selection?

Answer 20

individuals that are better suited to the environment are more likely to survive and reproduce. more beneficial alleles are passed on

Question 21

define evolution

Answer 21

change in allele frequency over time

Question 22

How does evolution come about?

Answer 22

variation in population due to mutation selection for individuals with beneficial alleles differential reproductive success changing the allele frequency over time

Question 23

what is the result of natural selection?

Answer 23

a species is better adapted to its environment

Question 24

What are the 3 types of adaptations?

Answer 24

anatomical, physiological, behavioural

Question 25

What does cross over result in?

Answer 25

different combination of alleles

Question 26

what phase of meiosis does crossing over and independent segregation take place?

Answer 26

Metaphase 1

Question 27

describe crossing over

Answer 27

chromatids of homologous pairs cross over and swap alleles

Question 28

what does independent segregation result in

Answer 28

different combination of chromosomes in each daughter cell

Question 29

Draw Meiosis diagram

Answer 29