PLANT REPRODUCTION

in plants

What is a petal?

A modified leaf that is often colorful and attracts pollinators

What is the receptacle in a generalised flower?

The thickened part of the stem that bears the flower and connects it to the plant.

Identify the part of the generalised flower that protects the flower when in bud. It is usually green

Sepals

What does an anther do?

An anther is the part of the stamen that produces pollen grains containing male gametes

A _______ holds the anther where it can best deliver pollen

Filament - stalk of the stamen that supports the anther.

The _____ is the sticky end of the style. Catches pollen grains

Stigma

The purpose of the style is to?

Elevate the stigma to receive pollen and provide a passage for pollen tubes to reach the ovary.

The ovary contains ____

ovules

An ovule contains an _____

Ovum

An _____ __ is the structure within the ovule that contains the female gametes

embryo sac

What is the micropyle in the ovule?

It is the opening in the ovule through which the pollen tube enters to fertilize the ovum.

What is the female part of a flower called?

Carpel, which consists of the stigma, style, ovule and ovary.

What is the male part of a flower called?

Stamen, which consists of the anther and filament.

What is pollination?

Pollination is the transfer of pollen from the anther to the stigmas of flowers.

Differentiate between self pollination and cross pollination

Self pollination occurs when a pollen grain is transferred from an anther to a stigma of the same flower or the stigma of another flower on the SAME plant

Cross pollination occurs when a pollen grain is transferred from an anther on one flower to a stigma of another flower on a different plant of the same species

Differentiate between the structure of a wind pollinated flower and an insect pollinated flower in terms of:

• Its flower

• Its petals

• Its pollen grains

• Its stamens

• Its stigmas

1. A wind pollinated flower is usually small and inconspicuous while the flower of an insect pollinated plants is large and conspicuous

2. The petals of wind pollinated flowers are often dull-colored and not scented, whereas insect pollinated flowers tend to have bright, fragrant petals to attract pollinators.

3. Wind pollen grains are lightweight and smooth, allowing them to be carried easily by the wind, while insect pollen grains are often sticky or spiky to attach to pollinators.

4. The stamens of wind pollinated flowers are often longer and more exposed to release pollen, while those of insect pollinated flowers are generally shorter and positioned to facilitate transfer to visiting insects.

5. The stigmas of wind pollinated flowers are often feathery or branched to catch drifting pollen, whereas insect pollinated flowers have sticky stigmas that effectively capture pollen from insects.

Describe the process of fertilisation in a plant

A pollen grain lands on thestigma,tabsorbs nutrients present,swells and develops a pollen tube

The pollen tube with 2 male nuclei and a tube nucleus in its tip grows down through the style by secreting digestive enzymes that digest a pathway

The pollen tube grows through the ovary wall and through the micropyle of the ovule and bursts.

The tube nucleus degenerates and one male nucleus fuses with the female gamete to form the zygote.

The other male nucleus and the two polar nuclei fuse to form the endosperm.

The zygote divides by______

Mitosis

The integuments become dry and develop into the ____

testa

A seed becomes ‘dormant’ when?

Water is withdrawn from it. Meaning germination is unable to occur.

Give 2 functions of fruits for seed

dispersal and protection

What are the 2 main types of fruits?

Succulent and Dry fruits

A fruit has __ scars

2 (one where it was attached to the parent plant and one where the style was attached)

What are the 2 reasons why seed dispersal is important?

It prevents overcrowding and therefore competition for light, water, co2, etc, allows plants to colonise new habitats

List 3 ways a fruit is adapted to be dispersed by animals

• Bright Colours to attract animals

• Contain stored food

• Seeds pass through digestive systems unharmed.

What structure do dry fruits develop for their dispersal and why?

They develop hooks that attach the fruits onto the fur of animals and human clothing

Fruits and seeds like the Combretum and Mahogany develop what structures to aid in their wind dispersal?

Wing-like structures that allow them to be carried by the wind.

How do hair-like extensions aid in the wind dispersal of a fruit?

They increase surface area, allowing the fruit to be carried further by the wind.

State how a succulent fruits

exocarp, endocarp and mesocarp adapt to be dispersed by water

The exocarp is typically waterproof, the mesocarp is initially fleshy but becmes dry to trap air and make the fruit buoyant, and the endocarp protects the seeds, allowing them to float.

How can dry fruits be dispersed by mechanical means?

Dry fruits can burst open to release seeds, using tension in the fruit's tissues to propel them away.