Biology

Question 1

What type of cell division leads to identical cells being formed?

Answer 1

Mitosis

Question 2

What type of cell division leads to non-identical cells being formed?

Answer 2

Meiosis

Question 3

What does sexual reproduction, in animals, involve?

Answer 3

The joining (fusing) of male and female gametes (sperm and egg)

Question 4

What does sexual reproduction, in plants, involve?

Answer 4

The joining (fusing) of gametes (pollen and egg cells)

Question 5

What does sexual reproduction lead to and why?

Answer 5

Variety in the offspring as there is mixing of genetic information

Question 6

What is asexual reproduction?

Answer 6

One parent (no fusion or mixing of genetic information) leading to genetically identical offspring

Question 7

What is a clone?

Answer 7

Genetically identical offspring (a result of asexual reproduction)

Question 8

What does meiosis do to the number of chromosomes in the gamete?

Answer 8

It halves it (46 to 23)

Question 9

What happens to the number of chromosomes during fertilisation?

Answer 9

It doubles (male and female gametes both have 23 chromosomes, combining to make 46)

Question 10

What key stages occur when a cell divides to form gametes (meiosis)?

Answer 10

1. Copies of the genetic information are made
2. The cell divides twice forming four gametes (each with a single set of chromosomes)
3. All the gametes are genetically different from each other

Question 11

What is the genetic material in the nucleus of a cell composed of?

Answer 11

DNA

Question 12

What is the structure of DNA?

Answer 12

A polymer made up of two strands forming a double helix

Question 13

What is DNA contained in?

Answer 13

Chromosomes

Question 14

What is a gene?

Answer 14

A small section of DNA on a chromosome

Question 15

What does a gene code for?

Answer 15

A particular sequence of amino acids, which make specific proteins

Question 16

What is the genome of an organism?

Answer 16

The entire genetic material of that organism

Question 17

Why is having the human genome sequence important?

Answer 17

It will be of benefit to medicine

Question 18

Why is understanding the human genome important?

Answer 18

• Genes linked to different types of disease can be searched for
• Inherited disorders can be understood / treated
• Migration patterns of the past can be traced

Question 19

Explain the term: gamete

Answer 19

A sex cell (e.g. sperm or egg)

Question 20

Explain the term: chromosome

Answer 20

A long molecule of DNA, found in the nucleus of a cell, which carries genes

Question 21

Explain the term: gene

Answer 21

A short section of DNA, found on a chromosome, carrying the instructions needed to make a protein (and so controls the development of a characteristic)

Question 22

Explain the term: allele

Answer 22

An alternative version of a gene

Question 23

Explain the term: dominant

Answer 23

The allele for the characteristic that’s shown by an organism if two different alleles are present for that characteristic

Question 24

Explain the term: recessive

Answer 24

An allele whose characteristic only appears in an organism if there are two copies present

Question 25

Explain the term: homozygous

Answer 25

Where an organism has two alleles for a particular gene that are the same

Question 26

Explain the term: heterozygous

Answer 26

Where an organism has two alleles for a particular gene that are different

Question 27

Explain the term: genotype

Answer 27

What alleles and organism has, e.g. Tt

Question 28

Explain the term: phenotype

Answer 28

The characteristics an organism has, e.g. tall

Question 29

Give an example of characteristics controlled by a single gene

Answer 29

Fur colour in mice / red-green colour blindness in humans

Question 30

What controls the phenotype (what is expressed)?

Answer 30

Alleles present (or genotype) operating at a molecular level to develop characteristics expressed (as a phenotype)

Question 31

Which allele is always expressed?

Answer 31

The dominant (even if only one copy is present)

Question 32

What are most characteristics a result of?

Answer 32

Multiple genes interacting (rather than a single gene)