33) Unit 2 - Sexual Investment

Question 1

Describe the sexual investment and the frequency of production of each of the following:

• egg
• sperm

Answer 1

• Eggs are large and have a greater energy store so require a larger energy investment
• They are produced infrequently
• Sperm are small and have less energy store so require a lower energy investment
• constantly made throughout life

Question 2

what are sessile organisms and give an example

Answer 2

organisms that are to fixed to a surface and therefore cannot move e.g. plants

Question 3

what is the problem surrounding reproduction for sessile organisms

Answer 3

• finding a mate

* making gametes meet

Question 4

what are the solutions surrounding reproduction for sessile organisms

Answer 4

• Mass release of gametes into the environment
• Use of other organisms to carry gametes e.g parasites or pollinating insects
• Hermaphroditism - self fertility e.g. plants
• very long penises to transfer sperm to other organisms

Question 5

List the two types of fertilization strategies

Answer 5

• Internal

* External

Question 6

Describe what internal fertilisation is and give 2 advantages and 2 disadvantages of it

Answer 6

Definition: when the sperm and egg fuse inside the female

ADV:
• fewer gametes needed to be released as chances of success are higher
•increased choice over choice of mate

DISAD:
•finding a mate increases chance of predation
•Interacting with opposite sex has risks revolving around parasitism

Question 7

describe what external fertilization is and give 1 advantage and 3 disadvantages

Answer 7

definition: hen the sperm and egg fuse outside the female

ADV:
•no increased exposure to predation

DISAD:
•more gametes required because chances of sucess are lower
•Little choice over mate
•relies on suitable environmental factors

Question 8

what is environmental factor is essential during external fertilization and why

Answer 8

water:
•prevents gametes from drying out
•gives a medium for sperm to swim

Question 9

what name and describe the types of parental investment are there

Answer 9

r-selected:
smaller organism that produce larger numbers of offpspring providing no parental care. Often have short life spans

k-selected:
Larger organism that produce lower numbers of offspring, providing more expensive parental care - Offspring have longer life spans

Question 10

why do females have more energy investment in reproduction

Answer 10

• Egg production

* Care of young

Question 11

Name and describe 2 reproductive strategies

Answer 11

Polygamy - an individual of one sex mating with several of the other sex

Monogamy - one male mating with one female

Question 12

when would polygamy be most likely used

Answer 12

when male does protection and females are responsible for care

Question 13

when would monogamy be used? and give an example

Answer 13

where higher parental investment is needed by both parents e.g birds for feeding