B5.1 Inheritance

Question 1

What is a gamete?

Answer 1

A gamete are sex cells (sperm or eggs)

Question 2

What is a chromosome?

Answer 2

Tightly packaged DNA around histone proteins

Question 3

What is a gene?

Answer 3

A section of DNA that can (but not always) code for a protein

Question 4

What is an allele?

Answer 4

Different versions of the same gene

Question 5

What is a dominant allele?

Answer 5

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

Question 6

What is a recessive allele?

Answer 6

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

Question 7

What is meant when an organism is homozygous?

Answer 7

When an organism has two copies of the same allele (two recessive or two dominant)

Question 8

What is meant when an organism is heterozygous?

Answer 8

When an organism has two different versions of the same gene (one dominant and one recessive)

Question 9

What is the genotype?

Answer 9

The genes present for a trait

Question 10

What is the phenotype?

Answer 10

The visible characteristic

Question 11

What is the genome?

Answer 11

All of the genes present in an organism

Question 12

What is discontinuous variation?

Answer 12

Variation that produces distinct categories (e.g. eye colour or blood groups)

Question 13

What is continuous variation?

Answer 13

Variation that cannot be placed into distinct categories and instead produces a spectrum (e.g. height, weight)

Question 14

What causes variation?

Answer 14

Mutations in the genetic code

Question 15

Describe how a mutation in a coding DNA sequence could be detrimental (Higher)

Answer 15

• The mutation may change the sequence of amino acids in the protein which will change its structure
• This may affect the protein, particularly in specific molecules like enzymes and antibodies

Question 16

What may happen if there is a mutation in non coding DNA? (Higher)

Answer 16

It may stop transcription and alter the expression of genes

Question 17

Give one advantage and one disadvantage of sexual reproduction

Answer 17

Advantage - It introduces variation

Disadvantage - It is slower and produces a limited amount of offspring

Question 18

Give one advantage and one disadvantage of asexual reproduction

Answer 18

Advantage - It produces lots of offspring quickly
Disadvantage - It does not introduce variation and so all offspring are susceptible to the same environmental pressures as the parents

Question 19

What is the difference between diploid and haploid cells?

Answer 19

• Haploid cells have half the amount of genetic information as diploid cells
• Haploid cells are germ cells
• Diploid cells are body cells

Question 20

What type of cell does meiosis produce?

Answer 20

Haploid germ cells (sperm and egg cells)

Question 21

How are dominant alleles represented in a punnett square?

Answer 21

They are represented using uppercase letters

Question 22

How are recessive alleles represented in a punnett square?

Answer 22

• They use the lowercase version of the same letter as the dominant allele

Question 23

Give 3 important findings of Gregor Mendel

Answer 23

• Organisms inherit hereditary units from their parents
• Offspring receive units from both parents and so share traits with both parents
• Traits can be passed on but not visible

Question 24

What discovery lead to people accepting Mendel’s ideas?

Answer 24

The discovery of the gene