Gen Bio 1 | SA2 Reviewer

Abiotic Pollination

pollination via wind (98%) and water (2%)

Why are the plants that are abiotically pollinated usually do not have colorful or scented flowers?

Since reproductive success does not require to attract pollinators, these parts are not needed.

Biotic Pollination

transfer of pollen from one flower to another through birds, insects and other animals

Coevolution

joint evolution of two interacting species, each in response to selection imposed by the other

Petals

attract pollinators

Sepals

protect the bud as the flower develops

Carpels

female portion of the flower

Stigma

receives the pollen

Style

pathway for pollen

Ovary

structure that will become fruit

Ovule

structure that will become seed

Stamens

male portion of the flower

Anther

houses pollen grains

Filament

supports the anther

Monocot Flower

Flower parts are in multiples of three

Dicot Flowers

flower parts are in multiples of four or fives

Complete Flowers

has all parts of a flower

Incomplete Flowers

lack one or more of the parts of the flower

Perfect Flowers

has both stamens and carpels

Imperfect Flowers

missing either stamens or carpels

Staminate

A flower that only has a stamen

Carpelate

A flower that only has a carpel

Self-Pollination

Pollination of a flower by pollen from the same flower or from another flower on the same plant

Cross Pollination

Pollen grains are transferred to a flower from a different plant

Life Cycle of Angiosperms

Pollination → Fertilization → Sporophyte → Gametophyte

Alternation of Generation

life cycle of a plant alternating between a sexual phase and an asexual phase

Sporophyte generation

non-sexual stage where plants grow and develop to become flowers

Spores

reproductive cells that flowers produce

Megaspore

large spore that germinates into a female gametophyte

Microspore

small spore that germinates into a male gametophyte

Gametophyte generation

sexual stage in plants where sperm cells develop from the male gametophyte (from pollen grains) and egg cells develop from female gametophyte (embryo sac)

Sporophyte

produces flowers in angiosperms

Development of spores

Inside the flower, diploid cells undergo meiosis to produce the haploid spores

How do gametophytes become sperm and egg cells

They develop by mitosis.

Anemophily

pollination via air

Hydrophily

pollination via water

Etemophily

pollination via insects

Chiropterophily

pollination via bats

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

Fruit Structure

A mature ovary of the flower that protects enclosed seeds and aids in their dispersal.

What happens to the other parts of the flower?

Stamens and petals fall out, and stigma and styles wither.

Pericarp

thickened wall of the fruit that came from the ovary wall

Exocarp

outer layer of pericarp

Mesocarp

middle layer of pericarp

Endocarp

inner layer of pericarp

Simple Fruit

Fruits derived from the ovary of a single carpel or several fused carpels; are either fleshy or dry

Simple Fleshy Fruits (Examples)

Berry, Hesperidium, Pepo, Drupe, Pome

Berry

• has a thin exocarp, soft fleshy mesocarp, and an endocarp enclosing one to many seeds

• examples are tomatoes and grapes

Hesperidum

berry with a tough leathery rind, common in citrus fruits

Pepo

specialized berry with a tough outer rind and fleshy mesocarp and endocarp, usually members of the squash family

Drupe

thin exocarp, fleshy mesocarp, and hard stony endocarp that encases seed; examples are cherries, plums, peaches, and coconuts

Pome

fruits that develop from flower parts other than ovary, examples include apples and pears

Accessory Fruits

fruit that develops largely from other tissues than the ovary

Apple as an accessory fruit

ovary is embedded to the receptacle, where the fleshy part is, only the apple core developed from the ovary

Simple Dry Fruit

can be dehiscent or indehiscent

Dehiscent Fruits

they crack open along two seams and shed their seeds into environment when fruit is ripe

Legume

from a single ovary with two rows of ovules, they split along two lines of dehiscence after drying, examples are peas and peanuts

Capsule

has more than one carpel, examples are lily and sweet gum

Lily as a Capsule

Lily is split length wise into sections corresponding to number of carpels

Sweet Gum Fruit as a Capsule

sweet gum fruit releases winged seeds as each ovary cracks open at maturity

Follicle

develop from a single ripened ovary and split once along its lengthwise seam they need to release their seeds; examples are milkweed and columbine

Indehiscent Fruit

they retain the seed and do not crack open after ripening

Achene

a single seed that is attached to the ovary wall at only one point; examples are sunflowers, dandelions, and buckwheat

Grain

its wall is thin, transparent, and firmly attached to all points of the seed coat; examples are corn and wheat

Samara

wind borne fruit with a single seed; examples are elms, maples, and ashes

Nut

one seeded fruits with hard, stony pericarps; examples are hazelnuts, chestnuts, and acorns

Aggregate Fruit

compound fruit that comes from the joining together of several ovaries of the same flower; examples are raspberries, blackberries, and strawberries

can be either true (raspberry) or accessory (strawberry)

Multiple Fruit

comes from an inflorescence, a group of flowers tightly clustered together, when the walls of many ovaries thicken, they fuse and become one fruit; examples include pineapple and jackfruit

Seeds

matured ovule that has embryo and endosperm within a seed coat

Endosperm development

develops before embryo; the central nuclei divide into a multinucleate supercell with a milky consistency

examples of liquid endosperm is coconut milk and solid endosperm is coconut meat

Monocot endosperms

occupies bulk of kernel and is the main energy reserve for the development of the young seedling as it stores the bulk of its energy in the endosperm; has one cotyledon

Dicot Endosperms

lack endosperms upon maturity, food reserves are completely transferred to the embryo; stores food in its to cotyledon

Embryo

young plant

Endosperm

stored food for embryo

Seed Coat

encases the seed

Radicle

embryonic root

Epicotyl

embryonic shoot

Hypocotyl

junction between roots and shoots

Cotyledon

seed leaf

Embryo Development

zygote undergoes mitotic division and gives rise to terminal and basal cell