reproduction in flowering plants objective: 1.describe the reproductive organs of the plant...

Reproduction in Flowering Plants

Objective:1. Describe the reproductive organs of the plant

2. Explain the process of sexual reproduction in angiosperms3. Describe the structure and function and structure of seeds

Homework: Learn about and describe different methods of seed dispersal

Quiz1. Why are the palisade and the spongy

mesophyll called the ‘working layers’ of the leaf?

2. What is cambium and what does it do?

3. How does the arrangement of the stomata leading into the spongy mesophyll (filled with air spaces) ensure chlorophyll containing cells have a constant supply of carbon dioxide for photosynthesis?

4. On board

Parts of a flower9Ad

Sexual Reproduction in Angiosperms

• Plants reproduce sexually

• The products of this sexual reproduction are seeds.

• These seeds are contained inside an ovary. Which develops into a fruit.

Reproductive PartsMale reproductive organs (stamen):• Anther: produces pollen grains• Filament: supports anther above

female reproductive organs

Female reproductive organs (carpel):• Stigma: sticky landing site for

pollen grains• Style: tube that leads down to

ovary• Ovary: contains ovules that

develop into seeds

Reproductive Mechanisms

Pollen (male gamete) from one plant lands

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stigmapollen

on the stigma of another plant. This is called pollination.

Methods of Pollination

• Natural Reproduction• Pollination in angiosperms can happen by

wind or animals.• Animals can transfer pollen (bees) from

one plant to the other.– They are called pollinators

• Pollen can be blown from one plant to another. – Wind dispersal

Reproduction

size

Selective breeding in plants

colourtaste

texture

Selective breeding and cross-breeding are carried out on plants to produce flowers and crops with desirable characteristics…

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9A Plant-breeding techniques

Anne the plant breeder chooses two parent plants with useful characteristics.

One plant will be the female parent. Anne removes the anthers and covers the flower with a bag. Why?

She puts the bag over the flower again. Later she collects the seeds and grows them to produce the new plant.

female parent

anthers removed

collected pollen

The other plant is the male parent. Its anthers develop as normal.

Anne collects its pollen and brushes it onto the female plant.

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From Pollen to Ovary

The pollen grain grows a pollen tube

pollen tube

ovary containing ovule

towards the ovary, which contains the ovule and egg cell (female gamete).

Fertilisation takes place when the ‘sperm’ nucleus from the pollen grain enters the egg cell. The resulting zygote eventually turns into a seed.

Fertilization9Ad

pollen tube with pollen grain nucleus

ovuleEmbryo grows inside the ovule.

egg cell

Compare

• With your neighbour, discuss how the reproductive system in plants is similar to

the reproductive system in humans.

Quiz

1. Name three different methods of seed dispersal.

2. Chose one method and explain how it effectively disperses seeds away from plant.

3. What are the male parts of the plant called?

4. What is it called when pollen from one plant lands on the stigma of another plant.

Comparing Plant and Human Reproductive Systems

Plant• Male and Female organs

• Male Gamete is pollen

• Female Gamete is egg produced in ovule

• Pollen nuclei fuses with egg nuclei (fertiliation)

• Diploid zygote

• Zygote grows into embryo

• Embryo grows inside protective seed coat

• Cotyledons provide nourishment

Human• Male or Female organs

• Male Gamete is sperm

• Female Gamete is egg produced in ovary

• Sperm nuclei fuses with egg nuclei (fertilization)

• Diploid zygote

• Zygote grows into embryo

• Embryo grows inside protective womb

• Placenta provides nourishment

Zygote to Embryo

The zygote will grow through the process of mitosis to form an embryo (The ovule is now called a seed and is covered by a protective seed coat.)

seed coat

food supply (cotyledon)

embryo

seed

Fruit Formation

• Some plants produce fruit containing seeds.

• Fruit: Mature ovary• Tissue surrounding the

embryo develops into fruit.

• When the fruit is fully developed it drops off the plant, or is carried away by an animal.

• When fruit decomposes it releases the seed and germination can occur.

Germination• A seed requires moisture (water) to germinate.• The as the embryo grows, the root and shoot

break through the seed coat.

• Nutrients stored in the cotyledon provide nourishment and support early development

Life cycle of an angiosperm

Plenary..

1. What is the function of the flower?

2. What is a seed?

3. What basic condition is required for a seed to germinate?

4. Describe two methods of pollination.