GEN BIO 1 | Sexual Reproduction in Angiosperns (copy)

Is a sporophyte a diploid or haploid?

A sporophyte is a diploid (2n).

Is a gametophyte a haploid or diploid?

A gametophyte is a haploid (n).

How many microspores are produced in the life cycle?

Four microspores

What does each microspore become?

A pollen grain

Where do microspores develop into gametophytes?

Pollen sacs

How many megaspores are produced?

Four megaspores

How many megaspores survive?

One megaspore

What happens to the surviving megaspore?

It divides three times through mitosis.

Development of embryo sac

has a seven celled structure and a single egg cell

Chalazal end

where three antipodal cells go to, they later disintegrate

Polar Nuclei

Also known as the central cell, two haploids move in the middle and join to form a diploid cell

Micropylar End

The entry of the embryo sac two synergid cells and the egg cell go to

Pollen Grains

Each have a large and small cell. The large cell becomes a pollen tube and the small cell is a two sperm nuclei

Pollination

A pollen grain lands on the stigma so a pollen tube emerges. When it reaches the ovule, it discharges the two sperm nuclei into the embryo sac.

Double Fertilization

• one sperm nucleus fertilizes the egg cells and forms the diploid zygote, a future embryo

• the other fuses with the central cell to form a triploid cell, a future endosperm

After Fertilization

Ovule develops into a seed, embryo with stored food surrounded by a seed coat. The ovary grows rapidly to form the fruit that protects and disperses the seeds.

Mechanisms of seed dispersal

To colonize new areas, reduce competition, and let their seeds prosper, plants use biotic dispersal agents and abiotic agents such as water and wind

The Purpose of Sexual Reproduction in Angiosperms

creates genetically diverse offspring

anemochory

wind dispersal

hydrochory

water dispersal

ballochory

explosion dispersal