Reproduction

Question 1

Define biological reproduction?

Answer 1

The process by which new individuals are produced from previously existing individuals
Two main types - asexual and sexual

Question 2

What is the difference between sexual and asexual reproduction?

Answer 2

asexual reproduction - an individual can reproduce without involvement with another individual of that species e.g. division of bacteria into two daughter cells
Sexual reproduction requires the involvement of two individuals, one of each sex. Generally, more complex organisms reproduce sexually

Question 3

What are the advantages and disadvantages of asexual reproduction?

Answer 3

Advantages - for animals that remain in one place, it allows the reproduction without the need to find a mate, numerous offspring can be produced without any great expenditure of energy or time and assumes a stable environment over time with the cloned offspring more likely to succeed in the same stable areas as their parents
Disadvantages - lacks adaptability and unresponsive to changing environments

Question 4

What are the advantages and disadvantages of sexual reproduction?

Answer 4

Advantages - recombination of maternal and paternal chromosomes in the gamete results in genetic variation among the offspring, in an environment which changes, this allows the process of natural selection to occur. Also most organisms evolve with their enemies, their predators, their competitors, their parasites and their pathogens, if you stop evolving they’ll catch up to you and youll be in trouble, the faster you can evolve the better off you are in this evolutionary arms-race
Disadvantages - two parents are required, only half of an individual’s genes are passed on per new individual and reproduction rates are less efficient

Question 5

Explain what is meant by internal and external fertilisation?

Answer 5

Internal fertilisation - the gametes are released into the female reproductive tract by the male during copulation and make their way to the oocyte
External fertilisation - the gametes are shed into the environment, and associate with each other by a random process - generally happens in lower vertebrates and invertebrates

Question 6

What are the sites of fertilisation for fish, amphibia, reptiles, birds, insects, mammals?

Answer 6

Fish - sea bed and river bed
Amphibia - reproductive tract
Reptiles - reproductive tract - infundibulum
Insects - abdominal reproductive tract
Mammals - oviduct

Question 7

What are the two functions of the testis?

Answer 7

1) production and transmission of male gametes (spermatozoa)

2) production of reproductive hormones (androgens)

Question 8

what cell types are found within and between seminiferous tubules and what occurs in these compartments?

Answer 8

Within ST - sertoli cells, sperm develops

Between ST - leydig cells, androgens aynthesised

Question 9

What are the three phases of spermatogenesis? Where does each phase occur?

Answer 9

Mitotic proliferation - basal compartment of tubule
Meiotic proliferation - adluminal compartment of tubule
Cytodifferentiation (spermiogenesis) - adluminal compartment of tubule

Question 10

What quantity of sperm is produced per second in the male?

Answer 10

300-600 sperm/g of testis produced per second