GCSE Biology, 4.6- Inheritance

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Describe the process of meiosis. [3 marks]

• All chromosomes are copied in cells.

• Cell divides into two.

• Cell divide one more time to form gametes.

Describe the process of fertilisation. [2 marks]

Gametes from both parents joined together sexualy.

Compare the advantage and disadvantage between sexual and asexual reproduction. [4 marks]

• Asexual reproduction is more time efficient than sexually reproduction.

• In Sexual reproduction, the offspring has variation, but offspring is genetically identical in asexual reproduction.

What is meant by ‘genome’. [1 mark]

Entire genetic material of organism.

Suggest 2 reason why is it important to study human genome. [2 marks]

• Search for gene that linked to a disease.

• Can treat inherited disorders.

State the name of the structure in the nucleotides.[3 marks]

a) Phosphate group.

b) Sugar molecule.

c) Base.

Base always paired on the opposite strand.

Give 2 paired base. [2 marks]

A-T, C-G

What is meant by ‘protein synthesis’. [2 marks]

Biological process of cell making specific protein which encoded by genetic information from DNA

Describe the process of protein synthesis.

[5 marks]

• The base sequence is copied into messenger RNA (mRNA) in nucleus.

• mRNA is passed out into cytoplasm.

• mRNA is attached to ribosomes.

• Amino acid are now brought to the ribosomes on transfer RNA.

• Ribosomes use the triplets of bases to join the correct amino acid in correct order and folded into unique shape.

What is meant by ‘allele’. [1 mark]

Version of gene.

What is meant by ‘homozygous’. [1 mark]

Two copies of same allele.

What is meant by ‘heterozygous’. [1 mark]

Two different allele.

What is meant by ‘dominant allele’. [1 mark]

Only require one allele to express their phenotype.

What is meant by ‘recessive allele’. [1 mark]

Require two same to express their phenotype.

What type of allele is cystic fibrosis. [1 mark]

Recessive.

What type is allele is polydactyly. [1 mark]

Dominant.

State two issue about embryo screening. [2 marks]

Unethical and expensive.