Chapter 18: Life Cycles and Reproductive Stratergies

Question 1

5 reproductive strategies in animals

Answer 1

1) Fertilisation strategies
2) Provision of Nutrients
3) Timing of Reproduction
4) Reproductive Behaviour
5) Protection of embryos and parental care

Question 2

Fertilisation strategies

Answer 2

• Fertilisation can be external – some aquatic animals release millions of eggs and sperm into the same area of water. - Fertilisation can be internal – in land animals the male deposits sperm in the female reproductive tract

Question 3

Provision of Nutrients

Answer 3

• Indirect development: Newly formed tiny organism must feed to provide food for further growth and involves an intermediate free living larval form before adult for is reached via metamorphosis. - Direct development: Individual is hatched or born in essentially adult form. Birds, Us.

Question 4

Timing of Reproduction

Answer 4

• External fertilisation is coordinated to occur at the same time in a region. - Timing of production of gametes and seasonal breeding (animals ‘on heat’). - Timing of implantation of blastocyst: can be delayed if a female falls pregnant too soon after giving birth.

Question 5

Reproductive Behaviour

Answer 5

Physical appearances, courtship behaviour, dominant male. All about selecting a ‘high-quality’ mate – good genes

Question 6

Protection of embryos and parental care

Answer 6

• Varies greatly from none (eg. Aquatic animals releasing gametes), to some (laying eggs in spots where there are no predators), to lots (mammals nourished by milk).

Question 7

diploid cell

Answer 7

has two sets (n) of genetic information, thus is 2n.

Question 8

haploid cell

Answer 8

has one set (n) of genetic information, thus is n. Two haploid cells/gametes fuse to form a diploid organism.

Question 9

two types of human intervention in pregnancy

Answer 9

IVF

Parental Testing

Question 10

IVF

Answer 10

In vitro fertilisation (IVF) – fertilisation occurs in the lab – success rates are LOW.

Question 11

Parental Testing

Answer 11

• Testing eggs – In humans meiosis produces 1 egg and other polar bodies. The polar bodies can be genetically tested.
• Test embryo – a cell (stem cell) can be removed from the blastocyst very early on before specialisation. • Amniocentesis – remove fluid from around fetus and test skin cells in it. • Chorionic villus sampling (CVS) – remove a small sample of fetal tissue to test. • Ultrasound is a safe prenatal test – uses reflected sound waves. Eg. Will Isaac Premature births – modern medicine can keep babies alive. Birth control also a form of intervention.

Question 12

Reproductive Strategies in Plants

Answer 12

Plants use self-fertilisation (asexual reproduction), cross-fertilisation and no fertilisation. Self fertilisation is good because you don’t need a mate but bad as it reduces genetic variation – opposite true of cross-fertilisation. Provision of resources to plant embryos is also variable