B16. Reproduction

Question 1

4 advantages of asexual reproduction

Answer 1

1. Faster
   - no mate/gametes needed / no need to wait to be pollinated (though single plants can reproduce sexually by self-pollination)
2. Offspring inherit all desirable qualities
3. Offspring will be well adapted to the same favourable environment
4. Plants that reproduce asexually usually store large amounts of food that allow rapid growth when conditions are suitable

Question 2

3 disadvantages of asexual reproduction

Answer 2

1. Since no variation from parent, offspring are unable to adapt to changing environment
2. Offspring would also have no resistance to disease if none in parent
3. Lack of dispersal leads to competition for nutrients. water and light (eg. potato tubers)

Question 3

3 advantages of sexual reproduction

Answer 3

1. Variation in offspring, so offspring are able to adapt to changing environment
2. Offspring may have resistance to disease due to variation
3. In plants, seeds are produced and can be dispersed away from parent plant to reduce competition

Question 4

2 disadvantages of sexual reproduction

Answer 4

1. 2 parents usually needed (though some plants can self-pollinate)
2. Growth of new plant to maturity from seed is slow because stored food is quickly used up during germination

Question 5

2 functions of the testa of a seed

Answer 5

1. Prevents embryo from being damaged

2. Prevents bacteria and fungi from entering seed

Question 6

5 measures of ante-natal care of pregnant women

Answer 6

1. Have a diet high in calcium, protein, iron & carbohydrate
2. Stop smoking
   - nicotine and carbon monoxide can cause baby to grow more slowly and be born smaller
3. Avoid alcohol consumption
   - baby at risk of being born smaller/having lower than average birth weight
4. Only take drugs if prescribed by doctor
5. Vaccinate against rubella
   - rubella virus can cause miscarriage, baby be born deaf/other disabilities

Question 7

Processes of birth

Answer 7

• Few weeks before birth, fetus lies head downwards, head above cervix
• Muscles in uterus wall contract
• Opening of cervix gradually dilates
• Amniotic sac breaks
• Few hours later, muscular contractions of uterus wall push baby down the cervix and the vagina
• The umbilical cord connecting baby to placenta is tied and cut
• Placenta falls off the uterus wall and is pushed out separately (afterbirth)

Question 8

2 adaptive features of an egg cell

Answer 8

1. Energy stores in cytoplasm (containing fats and protein for growth if egg is fertilised)
2. Jelly coat that changes after fertilisation (becomes impenetrable and prevents other sperm from entering and fertilising the cell)

Question 9

3 natural methods of birth control

Answer 9

1. Abstinence
2. Monitoring body temperature
3. Monitoring cervical mucus

Question 10

5 chemical methods of birth control

Answer 10

1. Intra-uterine device (IUD)
2. Intra-uterine system (IUS) - progesterone
3. Contraceptive pill - progesterone & oestrogen
4. Contraceptive implant - progesterone
5. Contraceptive injection - progesterone

Question 11

3 barrier methods of birth control

Answer 11

1. Condom
2. Femidom
3. Diaphragm

Question 12

2 surgical methods of birth control

Answer 12

1. Vasectomy (male sterilisation)

2. Female sterilisation (laparotomy)

Question 13

2 methods of transmission of HIV

Answer 13

1. Through sexual intercourse

2. Through blood contact