3b

Question 1

Genome

Answer 1

Entire DNA of an organism

Question 2

Gene

Answer 2

Section of DNA molecule that codes for a specific protein

Question 3

DNA molecule

Answer 3

• Two strands coiled to form a double helix
• Strands linked by:
• Adenine(A) & Thymine(T)
• Cytosine(C) & Guanine(G)

Question 4

RNA molecule

Answer 4

• Single stranded
• Contains Uracil (U) instead of thymine (T)

Question 5

Allele

Answer 5

Alternative form of a gene

Question 6

Dominant

Answer 6

An allele that is always expressed

Question 7

Recessive

Answer 7

An allele that needs 2 copies to be expressed

Question 8

Homozygous

Answer 8

Two of the same allele

Question 9

Heterozygous

Answer 9

Two different alleles

Question 10

Phenotype

Answer 10

What an organisms looks like

Question 11

Genotype

Answer 11

Which alleles an organism has

Question 12

Codominance

Answer 12

Alleles that are both expressed in the same phenotype. E.g. blood groups

Question 13

Polygenic inheritance

Answer 13

Features that are controlled by multiple genes with many alleles. E.g. eye colour, skin colour

Question 14

Diploid number of chromosomes in human cell

Answer 14

46

Question 15

Haploid number of chromosomes in human cell

Answer 15

23

Question 16

Mutation

Answer 16

A rare, random change in genetic material that can be inherited

Mutation chance can be increased by:
- Exposure to ionising radiation
- Chemical mutagens

Question 17

Chromosome

Answer 17

Carries genetic information in the form of DNA

Question 18

Transcription

Answer 18

• A protein splits DNA into two strands.
• From one of the two strands, an mRNA strand is constructed (everything remains equal to the other half but it binds adenine with uracil instead of thymine).
• This creates a messenger RNA (mRNA) strand

Question 19

Translation

Answer 19

• Ribosome binds to mRNA
• Transfer RNA(tRNA) reads the mRNA strip 3 bases at a time
• It attaches the corresponding amino acid of the 3-base pair to an amino acid chain
• A protein is synthesised from the amino acid chain

Question 20

Natural Selection

Answer 20

The process in which a species becomes better adapted to its environment.

• Variation from mutations
• Adaptation for selection pressure (temperature, diseases, competition for food…)
• Best adapted survive
• Reproduce
• Pass on alleles
• Repeated over multiple generations

Question 21

Codon

Answer 21

3 base pair that codes for an amino acid, found in mRNA.

Question 22

Anticodon

Answer 22

Complimentary 3 base pair found in tRNA. Matches with codon during translation