Reproductive strategies in animals

Question 1

What are reproductive strategies

Answer 1

Structural, functional and behavioural adaptations that improve the chances of fertilisation and/or improve the survival rate of organisms

Question 2

R strategists

Answer 2

• expend more energy for reproduction
• produces many offspring
• less energy for parental care
• many offspring die

Question 3

K strategists

Answer 3

• expend less energy for reproduction
• produces a small number of offspring
• expend more energy for parental care
• offspring have better chance of surviving

Question 4

survivorship curves

Answer 4

illustrate the no. of organisms that survive at different stages of their life span

Question 5

courtship

Answer 5

the behavioural patterns of female and male animals that lead to mating and ultimately offspring

Question 6

purpose of courtship

Answer 6

• ensures that both sexes are ready for mating
• helps to choose suitable mating partner
• helps to identify mating partners of the same species and so prevent unsuccessful mating between species, thus saving energy

Question 7

disadvantage of courtship

Answer 7

not everyone gets a chance to mate

Question 8

how courtship takes place

Answer 8

• visual stimuli
• sound stimuli
• chemical stimuli
• physical movements

Question 9

external fertilisation

Answer 9

• takes place in the water

- eggs are fertilized outside the female body

Question 10

disadvantage of external fertilisation

Answer 10

• predators reduce the probability of all the offspring surviving and reaching adulthood
• pollution
• dispersed by water current-reduces competition
• produce a lot more offspring - a lot of space available (takes place in water) (R strategists )

Question 11

internal fertilisation

Answer 11

• takes place inside the female’s body
• fewer gametes are produced - probability of fertilisation is much greater
• copulation
• in mammals - embryo receives protection and nutrition (from placenta)
• increases chances of sperm reaching the egg

Question 12

ovipary

Answer 12

yolk - food for embryo

shell - protects embryo against dehydration

Question 13

1. vivipary

Answer 13

• young are born live
• embryo develops into uterus
• internal fertilisation takes place
• if something happens to mother or placenta - no young

Question 14

2. vivipary

Answer 14

• source of food - placenta
• high chance of survival
• cannot produce a lot of offspring

Question 15

ovovivipary

Answer 15

• egg hatches inside the body
• internal fertilisation takes place
• protected against predators and unfavourable temps

Question 16

1. amniotic egg

Answer 16

• adapted for terrestrial life (life on land)
• after internal fertilisation - embryos enclosed in an egg with hard shell
• eggs develop extra-embryonic membrane (filled with fluid)

Question 17

2. amniotic egg

Answer 17

• prevents dehydration of embryo

- provides nutrients, water and oxygen to embryo while waste products are removed

Question 18

parental care

Answer 18

any behavioural pattern where parents spend time and/or energy on the feeding and protection of their offspring

Question 19

advantages of parental care

Answer 19

• feeding the young
• incubation of eggs
• guarding of eggs
• protection from predators
• keeping the young warm

Question 20

mammals

Answer 20

young receive milk from mother