Bio Reading (Ch 38)

Immediately after fertilization the triploid nucleus undergoes rapid _______ divisions to form a specialized nutritive tissue, the _______.

Mitotic / endosperm

Pollination in dioecious species is accomplished only when...

One plant pollinates another

Bee and wasp pollination

- Flowers are white, blue, and yellow (NOT red) - Strong UV light patterns - nectar guides

Bird Pollination

- big red tubular flowers - thin, high energy nectar - weak fragrance (birds are sight feeders, no sense of smell)

Butterfly flowers

- blue, yellow, or sometimes red - showy - deep corolla tubes

Fig Wasp Pollination

- host specificity by female wasps who lay eggs in gall forming fig ovaries but pollinate other ovaries - monoecious syconium

Bat pollination

- night blooming - white - robust - often hanging below crown

Moth pollination

- white flowers - long tubes - night blooming

Stamens

Male sex organs that contain the developing male gametophytes

A self incompatible species typically has....

Many alleles on the S locus

What are the two roles of the two cells in a pollen grain?

1. After pollination, the generative cell divided by mitosis to form two sperm cells that participate in fertilization 2. The tube cell forms the elongating pollen tube that delivers the sperm to the embryo sac These events occur after the pollen grain is transferred to a stigma

Double fertilization

1. Initially the pollen tube consists of two haploid cells, the generative cell and the tube cell. 2. The generative cell divides mitotically, producing two haploid sperm cells. One synergid cell degenerates when the pollen tube arrives 3. The sperm cells are released from the pollen tube 4. One sperm fertilizes the egg cell, forming the zygote, the first cell of the 2n sporophyte generation. 5. The other sperm cell fuses with the central cell, then the three nuclei combine, forming a 3n triploid nucleus (Pg 783)

Name the two processes double fertilization involves

1. One sperm fuses with the egg cell 2. The other sperm cell fuses with the central cell

What are the two main functions of fruit?

1. they protect the seed from damage by animals and infection by microbial pathogens 2. They aid in seed dispersal

What does the embryo use the endosperm for?

As a source of nutrients, energy, and carbon based anabolic building blocks.

Microspores: mitosis

Each of the four haploid products of meiosis undergo a single mitotic event, producing four two-celled pollen grains that are released into the environment.

Female gametophyte in angiosperms

Embryo sac

Carpels

Female sex organs that contain the developing female gametophytes

The ovary, together with the seeds it contains, develop into what after fertilization has occurred?

Fruit

Most angiosperm species are __________, and have flowers with both stamens and carpels.

Hermaphroditic (these are perfect flowers)

self-incompatibility

In a self-incompatible plant, pollen is rejected if it expresses an S allele that matches one of the S alleles of the stigma and style. Self pollen may 1) fail to germinate or 2) the pollen tube dies before reaching the ovule In either case, the egg cannot be fertilized by a sperm from the same plant

Where do pollen grains develop?

Inside the anther, which is apart of the stamen

What happens when a functional pollen grain lands on the stigma of a compatible stigma?

It germinates

The evolution of __________ made it possible for male gametes to reach the female gametophyte without an aqueous conduit.

Pollen

Male gametophyte in angiosperms

Pollen grain

Germination involves the development of the....

Pollen tube

In angiosperms, the plant we see in nature is a ______________ and the male/female gametophyte are contained in the __________.

Sporophyte / flowers

What is the structure for an angiosperm's reproduction?

The flower

What happens after the endosperm begins to develop?

The zygote undergoes mitotic divisions to form the new sporophyte embryo.

Megaspore: mitosis

Undergoes 3 divisions, producing eight haploid nuclei