BIO 1202 Test 3 (2 of 4)

function of the endosperm

In most monocots and some dicots the endosperm stores nutrients that can be used by the seedling after germination (phase where development goes to final step and the seedling comes out of the seed and grows) In other dicots the food reserves of the endosperm are exported to the cotyledons

which of the following is a potential advantage of introducing apomixis into hybrid crop species?

all of the desirable traits of the cultivar would be passed on to offspring

meiosis will produce microspores in the

anther

the ovary is most often located on/in the

carpel

Explain various methods that horticulturalists use to propagate plants from cuttings.

clones from cutting and grafting

stamen (filament and anther)

consists of filament and anther, vision a skinny green stalk with anther at the tips (male preproductive structure)

self-incompatibility

helps maintain genetic variability in a population

Recent research has shown that fertilization requires that carpels recognize pollen grains as "self or nonself." For self-incompatibility, the system requires

the rejection of self cells

what is endosperm?

via cotyledons, a source of food for the embryo - triploid

petals

you damn well better know where a petal is (often bright,but adapt for pollination types)

describe how a monocot and a dicot seed differ

Dicots - Hypocotyl(below cotyledon), radicle, and two thick cotyledons, epicotyl (above coty) Other dicots - Similar structures, but thin, longer, and more pronounced cotyledons. Still have hypo, epi, and cotyledons Monocots - Single cotyledon (scutelum), coleoptile(cover embryo), and coleorhiza (covers roots)

describe the edible portion of a peach

The edible portion of a peach is the pericarp, or fruit wall, which is a protective structure that encloses the seed and aids in its dispersal.

Describe the development of the embryo sac and explain the fate of each of its cells.

The entire process occurs in a tissue within each ovule called the megasporangium. Two integuments surround each megasporangium, except at a gap called the micropyle. Female gametophyte development begins when one cell in the megasporangium of each ovule, the megasporocyte, enlarges and undergoes meiosis, producing four haploid megaspores. Only one megaspore survives, the others degenerate. The nucleus of the surviving megaspore divides by mitosis three times without cytokinesis, resulting in one large cell with 8 haploid nuclei. The multinucleate mass is partitioned by membranes into a multicellular female gametophyte called the embryo sac.

what characterizes the fruit of seeds that are dispersed by the wind?

They have structures to extend the distance they travel on the wind.

development of the endosperm

after double fertilization, the triploid nucleus of the ovule's central cell divides, forming a multinucleate "super cell" that has a milky consistency. This liquid mass, the endosperm, becomes multicellular when cytokinesis partitions the cytoplasm by forming membranes between the nuclei. Eventually, these "naked" cells produce cell walls and the endosperm becomes solid.

gamete production order

1. Development of a female gametophyte (embryo sac) 2. meiosis 3. Ovule contains megasporangium 2n, megasporocyte 2n, integumenta 2n and a microphyte (n) 4. Surviving megaspore undergoes mitosis to develop 2 polar nuclei, and egg (n)

spore production

1. Development of a male gametophyte, pollen sac 2. Produces diploid microsporangium 3. Undergoes meiosis to produce 4 microspores haploid 4. Each of the 4 microspores haploid undergo mitosis 5. Male gametophyte has a tube cell, where pollen grain lands the tube that it goes through? (n) and a generative cell (n) ?? Purpose of these?

outline the process of double fertilization

1. If a pollen grain germinates, a pollen tube grows down the style toward the ovary 2. The pollen tube discharges two sperm into the female gametophyte (embryo sac) within an ovule 3. One sperm fertilizes the egg, forming the zygote. The other sperm combines with the two polar nuclei of the embryo sac's large central cell, forming a triploid cell that develops into the nutritive tissue called endosperm

Explain by which generation, structure, and process spores are produced.

Each microsporangium contains diploid microsporocytes (microspore mother cells) Microsporocytes divide by meiosis to produce microspores (diploid) Pollen grain becomes the mature male gametophyte Micro: male, mega: female

advantages and disadvantages of sexual reproduction

Each offspring is unique Pro: a lot of variability when environment changes Con: neither quick nor easy

distinguish between incomplete and complete flowers

Flowers that lack either stamens or carpels. Staminate flowers: lack carpel Carpellate flower: lacks stamens Plants with flowers of both sexes are monoecious (ex. Corn, maze) (incomplete) Plants that have flowers of one sex or the other are dioecious (incomplete) COMPLETE flowers have all four components

In general terms, explain how the basic plant life cycle with alternation of generations is modified in angiosperms

Flowers, double fertilization, and fruits are unique to this life cycle - review life cycle

explain how a fruit forms

Fruits form from the ovary of the flower and protects enclosed seeds and aids in dispersal by wind or animals. This occurs when the ovary wall becomes the pericarp, which is the thickened wall of the fruit.

describe the process of germination in a garden bean and corn plant

Germination depends on imbibition, which is the uptake of water due to the low water potential of the dry seed. Imbibing water causes the seed to expand and rupture its coat and also triggers metabolic changes in the embryo that enable it to resume growth. Following hydration, enzymes begin digesting the storage materials of the endosperm or cotyledons, and the nutrients are transferred to the growing regions of the embryo. The first organ to emerge from the germinating seed is the radical, which is the embryonic root.

Describe the development of a plant embryo from the first mitotic division to the embryonic plant with rudimentary organs.

Integuments of ovule develop into seed coat. Triploid endosperm cell divides to form endosperm that absorbs nutrients from the parent plant. The zygote develops into an embryo

Explain by which generation, structure, and process gametes are produced.

Megasporangium contains megasporocyte (megaspore mother cell) Megasporocyte undergoes meiosis producing four haploid megaspores (one survives) Megaspore undergoes 3 mitotic divisions to form the embryo sac

advantages and disadvantages of asexual reproduction

Offspring are clones Pro: can make a lot quickly and easily Con: little variability when environment changes

in angiosperms, each pollen grain produces two sperm. what do these sperm do?

One fertilizes an egg, and the other combines with two polar nuclei, which develop into stored food cells (endosperm).

how is fertilization in flowering plants different from fertilization in other plant groups?

One sperm nucleus fuses with the egg to form a diploid zygote, whereas the other sperm nucleus fuses with two polar nuclei to form a cell that develops into endosperm.

Describe the fate of the ovule and ovary after double fertilization. Note where major nutrients are stored as the embryo develops

Ovule turns into a seed, ovary turns into a fruit. As the embryo develops from the zygote, the seed stockpiles proteins, oils, and starch to varying degrees depending on the species. This is why seeds are such a major nutrient drain. Initially, carbohydrates and other nutrients are stored in the seed's endosperm but later, depending on the species, the swelling cotyledons of the embryo may take over this function

what is the difference between pollination and fertilization in flowering plants

Pollination is the transfer of pollen from an anther to a stigma. Fertilization is the fusion of haploid nuclei

distinguish between pollination and fertilization

Pollination occurs when a pollen grain lands on the stigma of a compatible plant; does not necessarily lead to fertilization Fertilization: sperm delivered to egg cell and endosperm in ovule; can screen to allow pollen to lead to fertilization

when is the pollen tube formed?

after a pollen grain is transferred to a receptive stigma and germinates, forming a tube that grows down through the style to the ovary of a flowering plant.

sepals

green leafy-like part at the base of the flower (modified leaves that close in over the flower)

gametophytic monoecious plant

S-genes are expressed on pollentube surface; pollen tube wont develop, fertilization wont occur

why do fleshy fruits often have seeds with very tough seed coats?

So the seeds can survive the mechanical forces and conditions in an animal's gut

grafting

a twig or bud from one plant is grafted onto a closely related species or a different variety of the same species

aggregate fruit

a whole lot of ovaries all with ovules, as the ovaries develop they all become one large mass and call the individual ovaries fruitlet ex: raspberry Results from a single flower that has more than one separate carpel, each forming a small fruit.

clones from cutting

plants are asexually reproduced from plant fragments

carpel (style, ovary, ovule, and stigma)

consists of stigma, style, and ovary. Ovary contains the ovule. Style is the stalk leading from the ovary to the stigma. Stigma at the tip of the style, where the pollen grain lands. (female preproductive)

self-recognition

depending on the plant, blocks pollen tube growth by one of two molecular mechanisms: gametophytic self-incompatibility or sporophyte self-incompatibility.

simple fruit

develop from single carpel, stamen and single ovary ex: pea

carpellate flowers

develop into fruits

dioecious plants

develop into two different flowers on the same plant

which of the following types of plants are incapable of self-pollinations?

dioecious

which of the following is an advantage of asexual reproduction in plants?

enhanced survival of genetiically favorable offspring

monecious plants

find a way to self pollinate, self-incompatibility

the primary function of the integument of an ovule is to

form a seed coat

which of the following is an example of sexual reproduction?

fusion of sperm and egg nuclei in an ovule

the germination of seeds depends on

imbibition

multiple fruit

many different carpels and each segment develops from the carpel of one flower. All of the carpels after fertilized will aggregate and come together to make one large fruit with multiple seeds inside. Instead of little packages (aggregate) they form one large mass. Ex: pineapple

in the life cycle of an angiosperm, which of the following stages is diploid

microsporocyte

apomixis

natural mechanism of vegetative reproduction in plants that is the asexual production of seeds; Diploid cell in ovule gives rise to embryo

fragmentation

natural mechanism of vegetative reproduction in plants that is the separation of parent plant into parts that develop into whole plants

fruits develop from

ovaries

which part of the flower develops into the seed?

ovule

which term describes the male gametophytes of flowering plants?

pollen grains

which structure formed by the male gametophyte allows sperm to reach the ovary of a flowering plant?

pollen tube

which process involves the transfer of pollen grains from an anther to a stigma?

pollination

what do fruits do?

protect seeds and aid in their dispersal

sporophytic monoecious plant

proteins are deposited onto surface of pollen grain by parent plant; will not allow pollen grain to penetrate to get to the ovule

order of floral organs from the outside to the inside of a complete flower

sepals -> petals -> stamens -> carpels

list four floral parts in order from outside to inside a flower

sepals, petals, stamens, carpels

a pollen produced by wind-pollinated plants is often smaller than the pollen produced by animal-pollinated plants.. A reason for this might be that

small pollen grains can be carried farther by the wind

self-incompatibility

the ability of a plant to eject its own pollen and sometimes the pollen of closely related individuals. If a pollen grain lands on a stigma of a flower of the same plant, a biochemical block prevents the pollen from completing its development and fertilizing an egg.

imbibition

the absorbition of water by the seed, caused the seed to expand and rupture

what provides food to the developing plant?

the endosperm