Topic 3

Question 1

Explain how a change in the DNA sequence of a gene can result in the production of a different protein? 4marks

Answer 1

• Changes the sequence of mRNA
• produced in transcription
• leads to different amino acids
• added by the tRNA
• this changes the shape/function of the protein

Question 2

What are some benefits that the Human Genome project could have for medicine?

Answer 2

• Locate genes associated with certain diseases
• Can personalise medicine
• Treat genetic disorders

Question 3

What is present in the DNA backbone

Answer 3

sugar, phosphate, attached to each sugar is a base

Question 4

Why is a mixture filtrated

Answer 4

To remove the insoluble material

Question 5

Describe how cells are broken down to release DNA

Answer 5

The cells are crushed and then mixed with detergent

Question 6

What are some benefits for discovering the sequence of bases for all plants and animals

Answer 6

Helps discover new medicines

Understand diesases

Track evolution

Question 7

What does genome mean

Answer 7

All the genetic material of an organism

Question 8

What is an allele and why might it happen

Answer 8

An allele is a different version of the same gene

It may occur due to a mutation in the gene sequence

Question 9

What are two bases held together by

Answer 9

Weak hydrogen bonds
A-T are held together by 2
G-C are held together by 3

Question 10

Why is ice-cold ethanol poured into the filtrate

Answer 10

To precipitate the DNA

Question 11

Explain why the enzyme protease is added to a mixture?

Answer 11

Protease breaks down protein
in the cell membrane or nucleus

Question 12

How is asexual reproduction beneficial to a farmer

Answer 12

It is quicker so more produce can be made which increase profit

Question 13

What is the sexual reproduction which produced gametes?

Answer 13

Meiosis

Question 14

Why is seed production an advantage to strawberries?

Answer 14

It introduced variation into the population
which allows for natural selection

Question 15

What are two precautions to take when blood is removed from a person?

Answer 15

Use a STERILE needle

Wear gloves

Question 16

Why does the sperm determine the sex of an offspring?

Answer 16

The sperm carries the X or Y chromosome.

XX results in a female

XY results in a male

Question 17

Explain how Mendel used homozygous tall and homozygous short pea plants to show that the tall allele is dominant to the short allele.

Answer 17

He crossed the homozygous tall and the homozygous short pea plants and produced a tall offspring, therefore the offspring had a heterozygous genotype with one tall and one short allele showing that the tall allele is dominant

Question 18

Explain one advantage to pea plants of using sexual reproduction to produce offspring?

Answer 18

It creates genetic variation which makes them more likely to survive a disease as it allows evolution

Question 19

Why is cell division by mitosis good for strawberries and the farmer

Answer 19

• Quicker to produce new plants
• Cheaper as don’t have to buy new seeds
• Best characteristics inherited from the parent

Question 20

Explain how the order of amino acids in a protein is determined by the sequence of the gene

Answer 20

• mRNA is transcribed from the gene in the nucleus
• mRNA binds to a ribosome
• The mRNA is matched by a complimentary tRNA
• tRNA transfers the amino acids to the polypeptide train in a specific order

Question 21

Explain the role of the active site of an enzyme

Answer 21

• Where the substrate binds and forms enzyme substrate complex
• A specific size for a specific substrate

Question 22

How do you convert from meters to nanometers

Answer 22

x10^9