Plant Reproduction

Sexual Reproduction in PlantsLink to the Edexcel Syllabus3.3 Describe the structures of an insect pollinated and a wind pollinated flower and explain how each is adapted for pollination.

Learning Objectives• Be able to identify and label the reproductive structures of a

flower, both wind and insect pollinated• Appreciate the structural adaptations that both wind and insect

pollinated flowers exhibit• Distinguish between the terms cross and self-pollination and

understand why and how flowers try to prevent self-pollination

Enhancement of learning• Show an appreciation of the potential impact that the depletion

in honey bee numbers may have on human populations

Flowers are the reproductive organs of plants

Structure and function of the flower

stigma

style

ovary

ovule

carpelfilament

stamen

petal

sepal

receptaclepeduncle

anther

Flower Structure Quiz

• What is the name of the structure labelled X in the diagram?

B. sepal

C. stamen

D. peduncle

A. carpel

X

Flower Structure Quiz

• Where is pollen made?

A. stigma

B. sepal

C. anther

D. ovary

Flower Structure Quiz

• Where is the ovule found in a flower?

A. petals

B. style

C. nectary

D. ovary

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Flower Structure Quiz• Which parts of the flower are labelled below:

B. X = filament, Y = anther

X

YC. X = stigma, Y = style

D. X = anther, Y = filament

A. X = style, Y = stigma

Pollination

The pollen grain contains the male sex cell (gamete)

Pollination is the transfer of pollen from the anther to the stigma

Pollen can be carried between flowers by insects or by wind

Wind-pollinated flowers are different in structure to insect pollinated flowers as they do not have to attract insects to them

but do need to be exposed to the wind.

Petals are small and green as there is no need to attract insects

Stigmas are feathery to catch pollen carried in wind

Anthers are exposed to the wind so that pollen can easily be blown away

Pollen grains are very small and light. They occur in very large numbers

No scent or nectary

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Insect-pollinated flowers are adapted to attract insects to enable the transfer of pollen

Sticky stigma to collect pollen Brightly coloured

petals

nectar and a scent present

Pollen has barbs for hooking onto insect fur

Anthers positioned to rub pollen onto insects

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Pollination can be self pollination or cross-pollination

This is an example of cross-pollination as the pollen travels from one flower to a different flower.

Self-pollination occurs when pollen falls from the anther ontothe stigma of the same flower

Self-pollination is not desirable as it reduces genetic variation

Flowers will prevent self-pollination by either having stigma above stamen or…

…by having stamen and stigma mature at different times.

Pollination Quiz

• Pollination is the transfer from….?

A. stigma to anther

B. style to stamen

D. anther to stigma

C. ovule to filament

Pollination Quiz

• The two mechanisms for pollination are?

A. Wind and water

C. Insect and water

B. Insect and wind

D. Wind and birds

Pollination Quiz

• Cross-pollination…

A. Increases genetic variation

B. Decreases genetic variation

D. Is only performed by wind

C. Is only performed by insects

Pollination Quiz

• Flowers are adapted for wind-pollination by…

C. Having feathery stigmas

B. Having a nectary

A. Having bright petals and a scent

D. Having sticky stigmas