Sexual Reproduction in Plants and Animals

• Interpret diagrams of formation of egg and sperm.

• Explain fertilization in animals and plants.

• Compare advantages / disadvantages of asexual and sexual reproduction

KEY WORDS Stamen Pollen Ovary

Sperm Pistil Testes

Gonads Embryo

Gametes produced in reproductive organs called gonads.

Male gonad called testes.

SPERMATOGENESIS

Only 1 egg cell receives enough cytoplasm to survive.

Female gonads called ovaries.

OOGENESIS

Meiosis is necessary for gametes to be produced.

Once fertilization has occurred, mitosis is used to reproduce the single cell until an embryo is produced and eventually birth occurs.

The zygote must receive food, moisture, warmth and protection.

The embryo develops and matures through mitosis.

Plants:Male gamete – pollen (from stamen)Female gamete – egg (from pistil)

• Pollen transferred to pistil.• Fertilizes many eggs producing zygotes.

• Develop into seeds. • Ovary develops into fruit.

Asexual Reproduction Sexual Reproduction

One parent Two parents

Meiosis - gametes

One offspring

Combination of both parents genes.

High variation due to gamete production and

fertilization.

Mitosis - daughter cells

Two offspring

Genetically identical to parent.

No variation unless due

to mutations.

Asexual Reproduction:Advantages Disadvantages

Less chance for evolution

Can lead to overcrowding and

competition for survival.

Genetically identical organisms are more

vulnerable to disappearing because of a catastrophe or

disease.

No need to find a partner

Less energy is required to reproduce.

Offspring are well adapted to the environment because of the success of the parent.

Fast – can take over an area quickly by

reproducing.

Advantages DisadvantagesSexual Reproduction:

Slow – finding a partner and producing gametes takes time.

Lots of energy used to make gametes and attract a mate.

The genetic results of meiosis and often fertilization, are

unpredictable

Genetic "errors" happen more frequently because meiosis is more complex

than mitosis.

Increases genetic variation in a species - more evolution

Only the “strongest ” will be able to reproduce allowing

the best qualities to be passed on to new

generations.

Variations guarantee that a higher proportion will survive in cases of

catastrophe or disease.

Two parents to watch over offspring

In sexual reproduction:“Only the strong survive”

Most species have developed ways to ensure that the “best” genetics are passed on to future generations.

Things that enhance reproductive success are called – adaptations.

Examples of adaptations that enhance reproductive success:

Behavioural • caring for their young• mating calls / dances• fighting

Those best able to modify their behaviour or appearance are most likely to survive and

reproduce.

Physical• bright colours / size• pheromones • multiple offspring

1. List some adaptations that humans have deveoloped to show they are “strong” and to attract a mate for reproduction.

- build their muscles

2. List 10 slang terms for male genitalia. - “daddy buttons”