Chapter 20: Reproduction in Plants

Tince food

________ is usually present in the vegetative structures,

gametesNatural vegetation

There is no fusion of two reproductive cells called ________.

germination

Hypogeal ________ where the cotyledons remain below the surface of the soil.

pollen

The ________ moves down the ________ tube to the ovule.

Define asexual reproduction.

It is the "production of new individuals" that does "not involve fertilization", i.e no fusion of two gametes.

What is natural vegetation?

It is a form of "asexual reproduction", involving the "growth of a new daughter plant" from any part of an old plant.

Mention a few advantages of natural vegetation.

Advantages of natural vegetation are:

• the "process does not need external agencies".

• "buds can develop rapidly into daughter plants".

• the daughter plants resemble the parent plant in every way. Beneficial or desirable qualities in the parent plant are passed on directly to the young plants without any change.

• the process involves only one parent, and no fertilization is required.

• since plants are already in a suitable habitat, they can colonise the area more rapidly.

Mention a few disadvantages of natural vegetation.

Disadvantages of natural vegetation are:

• lack of any dispersal mechanism may lead to "overcrowding", "causing the new plants to compete for light and food".

• the "new plants are less varied" compared to those produced by seeds, thus they may be "less adaptable to changes in environmental conditions".

Define sexual reproduction.

It is the "fusion" of special cells called "gametes".

What is the role sepal in a flower?

It is the "modified leaves" which enclose and "protect the other parts of the flower" in the bud stage.

What is the role of petal in a flower?

They are the modified parts of the flower, They have two important roles; they are brightly coloured to "attract insects for pollination" and they provide a "landing platform for insects".

What is the role of stamen in a flower?

It is the male part of the flower, its man role is to "produce pollen grains".

What is the role of carpel in a flower?

It consists "ovary".

What is meant by pollination?

It is the "transfer of pollen grains" from the "anther to the stigma".

How are flowers pollinated by insects?

They are pollinated when:

• "insects are attracted to the plant", where pollen sticks to them.

• "they then move to another plant and drop the pollen", causing the second plant to be pollinated.

• pollen that is carried by insects is "adapted to be sticky and have hooks which attach to the insect".

How are flowers pollinated by wind?

They are pollinated when:

• the "wind blows pollen off the first plant" and "carries it to the second plant".

• pollen carried by the wind "does not need to stick to anything", thus its smooth. It is also "very light".

How does fertilization occur in flowers?

They are fertilized in the following steps:

Define germination.

It is the process during which the "food reserves present in a seed are broken down" and the "embryo starts to grow into a plant".