Genetics

Question 1

Explain one advantage of sexual reproduction

Answer 1

Inherit different alleles
Which gives greater variation in species/characteristics
So will be able to survive (in diff environments)

Question 2

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

Answer 2

Genetic variation increases
So more likely to survive a disease/environmental change

Question 3

Explain why asexual reproduction in strawberries is beneficial to strawberry farmers

Answer 3

Rapid reproduction technique
Higher crop yield/ no requirement for cross pollination

Question 4

Explain why seed production is an advantage to strawberry plants

Answer 4

Introduces variation in population
Which allows for natural selection of fitter plants/increased chance of population surviving

Question 5

Process that forms gametes for sexual reproduction

Answer 5

Meiosis

Question 6

Name the type of reproduction involving flowers

Answer 6

Sexual reproduction
• variation in offspring

Question 7

Explain why the enzyme protease was added to the mixture to extract DNA from fresh peas

Answer 7

• protease breaks down proteins
• in the cell membrane
• destroys enzymes that may break down the DNA

Question 8

State why ice cold ethanol was poured into the filtrate

Answer 8

To precipitate the DNA (as DNA is insoluble in ethanol)

Question 9

What are two strands of DNA held together with?

Answer 9

Weak hydrogen bonds

Question 10

Define alleles

Answer 10

Different versions of the same gene

Question 11

Define genome

Answer 11

All the genetic material of an organism

Question 12

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

Answer 12

• discover new medicine/find a cure
• identify useful genes
• track evolution
• identify the sequences that allow some plants and animals to cope with environmental change

Question 13

DNA can be extracted from fruit.
Describe how cells are broken down to release DNA

Answer 13

• homogenise cells (crush cells)
• mix cells with salt/detergent

Question 14

Describe how base pairs are bonded together in a DNA molecule

Answer 14

• held together by weak hydrogen bonds
• complementary bases
• A-T / G-C

Question 15

Structure of DNA

Answer 15

• polymer
• four bases (A,T,G,C)
• complementary base pairs
• weak hydrogen bonds join bases
• two strands of DNA
• double helix
• nucleotides

Question 16

Describe how DNA can be extracted

Answer 16

• crush/grind cells
• add detergent
• heat in water bath
• add ice cold ethanol
• DNA forms as a precipitate

Question 17

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

Answer 17

• changes mRNA sequence
• produced in transcription
• leads to a different amino acid (in polypeptide sequence)
• changes shape/function of the protein

Question 18

Benefits of the Human Genome Project

Answer 18

• locate genes associated with diseases
• treat (genetic) disorders
• personalised medicine