Biology 200 Chapter 23: Angiosperms

Flashcards covering the characteristics, development, fertilization, and pollination ecology of Angiosperms based on Chapter 23.

What are angiosperms?

Flowering plants whose seeds are enclosed in a carpel.

In angiosperms, what structure does the carpel resemble?

A leaf that has folded over and fused at the margins.

What is a pistil composed of?

A single carpel, or two or more united carpels.

From what structure does the seed develop in angiosperms?

The ovule within the carpel.

What does the ovary of an angiosperm become after fertilization?

A fruit.

Into which phylum are ALL angiosperms grouped?

Phylum Magnoliophyta

What are the two large classes within Phylum Magnoliophyta?

Magnoliopsida (Dicots) and Liliopsida (Monocots)

What is the formal description of a flower?

A modified stem bearing modified leaves.

Describe the characteristics of the most primitive flower.

A long receptacle with many spirally arranged, separate parts not differentiated into sepals and petals, and numerous flattened stamens and carpels.

Approximately how many species of angiosperms are parasitic?

Approximately $4,000$ species.

How do parasitic plants obtain nutrients?

They intercept food and water in the xylem and phloem of a host.

Identify two examples of saprophytic plants mentioned in the text.

Some orchids and the Snowplant.

Are angiosperm sporophytes or gametophytes dominant?

Sporophytes are dominant.

What characterizes the mature male gametophyte in angiosperms?

A germinated pollen grain with three nuclei.

What diploid cell differentiates within the ovule to produce megaspores?

The megasporocyte.

How many haploid megaspores are produced after meiosis, and how many survive?

Four haploid megaspores are produced, and three degenerate.

What do the outer two layers of the ovule (integuments) eventually become?

The seed coat.

Where is the micropyle located?

At one end of the ovule.

How many nuclei and cells make up a typical mature female gametophyte (embryo sac)?

$8$ nuclei and $7$ cells.

What three cells are found closest to the micropyle in the female gametophyte?

The egg and two synergids.

What are the three cells at the opposite end of the micropyle called?

Antipodals.

Where does the formation of male gametophytes occur?

Inside the anthers.

What quartet of cells is produced when a microsporocyte undergoes meiosis?

Haploid microspores.

Into what two cells does a microspore divide during mitosis?

A small generative cell and a larger tube cell.

What is the alternative name for the nucleus of the tube cell?

The vegetative nucleus.

What is the outer, finely sculptured layer of a pollen grain wall called?

The exine.

How is pollination defined in the context of angiosperms?

The transfer of pollen grains from the anther to the stigma.

What is the term for when pollen grains germinate on the stigma of the same flower?

Self-pollination.

What path does the pollen tube take to reach the ovule?

It grows between the cells of the stigma and style until it reaches the micropyle.

What does the generative cell divide into during pollen tube growth?

Two sperm.

What happens when the pollen tube enters the female gametophyte?

It destroys a synergid and discharges the sperms.

What occurs during Double Fertilization regarding the zygote?

One sperm unites with the egg to form a zygote, which then becomes the embryo.

What occurs during Double Fertilization regarding the endosperm?

One sperm unites with the central cell nuclei, producing a triploid ($3n$) endosperm nucleus.

What is the function of the endosperm tissue?

It acts as nutritive tissue for the embryo.

Which plants provide a major source of human nutrition due to their nutritional endosperm?

Wheat, rice, and corn.

In most dicots, what happens to the endosperm?

It is absorbed into the cotyledons.

In lilies, what is the ploidy of the endosperm nucleus resulting from fertilization?

It results in a $5x$ endosperm nucleus.

Define Apomixis.

The development of an embryo from a diploid nutritive cell or other cell of the ovule without the fusion of gametes.

What is Parthenocarpy?

The development of fruit from ovaries with unfertilized eggs, resulting in seedless fruits.

Name two examples of fruits resulting from parthenocarpy.

Navel oranges and bananas.

According to the fossil record, when did flowering plants first appear?

About $160$ million years ago during the late Jurassic.

What are the characteristics of primitive flowering plants?

Simple leaves, numerous spirally arranged parts, radially symmetrical (regular), and both stamens and pistils (complete and perfect).

What is a superior ovary also known as?

A hypogynous flower.

What are the characteristics of specialized flowering plants?

Fewer parts in definite numbers, whorled arrangements, bilaterally symmetrical (irregular), and often incomplete or imperfect.

What is an inferior ovary also known as?

An epigynous flower.

What is a perigynous flower?

A flower where parts are attached to a floral tube (fused petals) that is not attached to the ovary.

What defines an incomplete flower?

A flower that is missing the corolla or other flower parts.

What is the difference between monoecious and dioecious species?

In monoecious species, male and female imperfect flowers are on the same plant; in dioecious species, a plant bears only male or only female flowers.

What colors are bee-pollinated flowers generally, and what do they often feature?

Brightly colored, mostly blue or yellow, often with honey guides visible in UV light.

Describe the characteristics of beetle-pollinated flowers.

Strong, yeasty, spicy, or fruity odors; white or dull in color.

How do fly-pollinated flowers attract their pollinators?

They smell like rotten meat and are often dull red or brown.

What are the traits of bird-pollinated flowers?

Bright red or yellow colors, little odor, copious nectar, and long floral tubes.

When do bat-pollinated flowers open, and where are they primarily found?

They open at night and are primarily found in the tropics.

What are pollinia?

Little sacs containing pollen grains, often found in orchids, with sticky pads at the base.

What are herbaria?

Libraries of dried, pressed plants, algae, and fungi that are arranged and labeled.