Inheritance

Question 1

What is a gene?

Answer 1

A section of DNA that codes for a specific protein (eg melanin or keratin) to produce a particular characteristic.

Question 2

What is a chromosome?

Answer 2

A long DNA molecule that is found in a cell nucleus, and has many genes in it. It has stabilising proteins.

Question 3

How is the structure of DNA composed?

Answer 3

Two parallel strands called backbones, which are made of sugar (deoxyribose) and phosphate. They are joined together in regular intervals by pairs of bases (A, T, C and G). The molecule is twisted, forming a double helix.

Question 4

What are nucleotides made of?

Answer 4

• Bases (A, T, C and G)
• Sugar (Deoxyribose)
• Phosphate

Question 5

What are the four bases?

Answer 5

• Adenine (A)
• Thymine (T)
• Cytosine (C)
• Guanine (G)

Question 6

Which bases always pair up?

Answer 6

• Adenine and Thymine
• Cytosine and Guanine

Question 7

Why is DNA shaped as a double helix?

Answer 7

It is more stable

Question 8

What do genes do?

Answer 8

Provide instructions for the cell to make proteins.

Question 9

Which is important for controlling the proteins made, the bases, or their sequence?

Answer 9

The sequence of the bases

Question 10

What is a mutation in DNA?

Answer 10

When something goes wrong when copying the DNA to make proteins.
OR
A change in the DNA sequence

Question 11

What are some common mutations in DNA?

Answer 11

• THE CAT ATE THE FAT RAT (normal)
• THE CAT ATE THE FAT TAR
• THE CAT ATE THE FAT BAT
• THE CAT TET HEF ATR AT

Question 12

How many chromosomes do human body cells contain?

Answer 12

46

Question 13

How many pairs of chromosomes do human body cells contain?

Answer 13

23 pairs, one from your mother, one from your father.

Question 14

How many copies of each gene do you have, and do these copies have to be the same?

Answer 14

2 copies of each gene, and no they must not be the same.

Question 15

How many chromosomes do human gametes contain?

Answer 15

23, and are haploid

Question 16

What are the sex chromosomes in humans called?

Answer 16

X and Y
(XX is female, XY is male)

Question 17

What must happen to chromosomes during cell divison?

Answer 17

They must be accurately copied and passed on.

Question 18

What is cell division?

Answer 18

The process of replicating cells to make new ones.

Question 19

What are the two types of cell divison?

Answer 19

Mitosis and meiosis.

Question 20

Describe the process of mitosis.

Answer 20

Question 21

How long does mitosis take?

Answer 21

At its fastest, one hour.

Question 22

What is mitosis used for?

Answer 22

• Growth/repair of tissues (replacement)
• In asexual reproduction
• Cloning

Question 23

What cell cannot duplicate?

Answer 23

Nerve cells cannot perform mitosis, and therefore can never repair. Once damaged, they cannot be fixed.

Question 24

Describe the process of meiosis.

Answer 24

Question 25

What is meiosis used for?

Answer 25

Creating Gametes

Question 26

What is crossing-over?

Answer 26

When homologous chromosome pairs exchange DNA to create genetic variation.

Question 27

How many cell divisions take place in mitosis?

Answer 27

One

Question 28

How many cell divisions take place in meiosis?

Answer 28

Two

Question 29

How many daughter cells are created in mitosis?

Answer 29

Two

Question 30

How many daughter cells are created in meiosis?

Answer 30

Four

Question 31

What is an allele?

Answer 31

A different version of the same gene.

Question 32

What does homozygous mean?

Answer 32

When both alleles are the same (eg BB or bb)

Question 33

What does heterozygous mean?

Answer 33

When both alleles are different (eg Bb)

Question 34

What is the genotype?

Answer 34

Which alleles you have (eg BB, Bb or bb)

Question 35

What is the phenotype?

Answer 35

The outward expression of the alleles you have / your appearance. (eg blue eyes)

Question 36

What is a dominant allele?

Answer 36

You only need one allele present for the characteristic to be expressed in the phenotype.

Question 37

What is a recessive allele?

Answer 37

You need two copies of the same allele for the characteristic to be expressed in the phenotype.

Question 38

What is a codominant allele?

Answer 38

When two alleles of the same gene are both expressed in the phenotype.

Question 39

What does diploid mean?

Answer 39

The full number of chromosomes are in the cell (46 in humans) and there are two of each pair of chromosomes.

Question 40

What does haploid mean?

Answer 40

Half the number of chromosomes (gametes only) and there is only one of each pair of chromosomes.