B13

Question 1

What happens during the first stage of meiosis?

Answer 1

Chromosomes pairs line up alomg the centre of the cell

The pair of chromosomes are seperated and move to opposite poles of the cell

Chromosome number is halved

Question 2

What happens during the second stage of meiosis?

Answer 2

Chromosomes line up along the centre of the cell

Chromatids are seperated and move to opposite poles

Four haploid gametes are produced

Question 3

What is the advantage of sexual reproduction?

Answer 3

Creates genetic variation

Increase chance of a species adapting to its enviroment

Question 4

What are disadvanatges of sexual reproduction?

Answer 4

Two parents are needed

More time and energy is required?

Question 5

Describe advantages pf asexual reproduction?

Answer 5

Onnly needs 1 parent
Quicker than sexual reproduction
Requires less energy and time

Question 6

What is the disadvantage of asexual reproduction?

Answer 6

No genetic variation reducing the chance of a species being able to adapt to enviromental change

Question 7

Describe the circumstances in which malaria paristes reproduce sexually and asexually?

Answer 7

Sexual in the mosquito

Asexually in the human host

Question 8

Describe the circumstances in which fungi reproduce sexually and asexually?

Answer 8

Asexually by spores

Sexually to give variation

Question 9

Describe the circumstances in which plants reproduce sexually and asexually?

Answer 9

Sexually to produce seeds

Asexually by runners

Question 10

Define genome?

Answer 10

The entire genetic material of an organisms

Question 11

Why is understanding the human genome importanr?

Answer 11

Searching for genes linked to different types of disease

Understandinf and tresting inherited disorders

Question 12

What are the monomers of dna?

Answer 12

Nucleotides

Question 13

What are DNA nucleotides made up of?

Answer 13

Common sugar
Phosphate group
One of the 4 bases: A, T, C or G

Question 14

What is proteinsynthesis?

Answer 14

Formation of a protein from a gene

Question 15

How many chromosomes do human body cells have?

Answer 15

46 chromosomes (23 pairs)

Question 16

How many chromosomes do human gametes have?

Answer 16

23 chromosomes

Question 17

Define gene?

Answer 17

A small section of dna that codes a specific function

Question 18

What is a mutation?

Answer 18

A random chnage in the base sequence of DNA

Question 19

What is a dominant allele?

Answer 19

A gene where only one copy is needed for it to be expressed

Question 20

What is a recessive allele?

Answer 20

A gene where two copies are needed for it to be expressed

Question 21

What is meant by homozygous?

Answer 21

When an individual has two identical alleles

Question 22

What is menat by heterozygote ?

Answer 22

An individual with different alleles

Question 23

What is the genotype?

Answer 23

The genes present for a trait

Question 24

What is the phenotype?

Answer 24

The visible characteristics

Question 25

What is an inherited disorder?

Answer 25

A disorder caused by the inheritance of certain alleles

Question 26

Give 2 examples of inherited disorders?

Answer 26

Polydactyl - (having extra fingers or toes, caused by a dominant allele) Cystic fibrosis - (disorder of cell membranes, caused by a recessive allele)

Question 27

What are ethical issues concerning embryo screening?

Answer 27

Destruction of embryos is unethical and seen as murder Religious beliefs It could lead to beliefs in society thag a disabled child is inferior

Question 28

What are social issues concering embryo screening?

Answer 28

Social care for children with inherited disorder if parents don’t want to provide care Parent could decide to terminate the embryo to avoid suffering in the future due to the disorder

Question 29

What are the chromosomes for males?

Answer 29

X and Y

Question 30

What are the chromosomes for females?

Answer 30

X and X

Question 31

Why are men more likely to show the phenotype for a recessive sex-linked trait then women?

Answer 31

Many genes are found on the X chromosome that have no counterpart in the Y chromosome Women have two alleles for each sex linked gene whereas men often have only one allele, only one recessive allele is required to produce the recessive phenotype in males