Ch38

In a typical angiosperm, what is the sequence of structures encountered by the tip of a growing pollen tube on its way to the egg? 1. micropyle 2. style 3. ovary 4. stigma

4 → 2 → 3 → 1

If an ovary contains 50 ovules, what is the minimum number of pollen grains that must land to form 50 mature seeds?

50

Suppose that 100 pollen grains land on a stigma, and 50 mature seeds are formed in the fruit. What does this indicate about the pollination process and success?

50% success: 50 sperm fertilized 50 eggs, and 50 sperm fused with 100 polar nuclei.

Select the correct statement(s) about angiosperm seeds.

An angiosperm seed contains structures contributed by three generations of plants.

Which of these represents the female gametophyte generation of an angiosperm?

An embryo sac

Which of these structures is/are produced by fertilization of egg and sperm?

An embryonic sporophyte

Which of these represents the male gametophyte generation of an angiosperm?

Cells within a pollen grain

Fruit ripening represents an example of positive feedback. Which one of the following statements accurately justifies why the process of fruit ripening involves positive feedback?

Chemical signals initiate a process that triggers enzymatic activity, which involves converting starches into sugars, softening of pulp, and color change of fruit.

Select the correct statement about double fertilization in the angiosperm life cycle.

Double fertilization produces a diploid sporophyte and a triploid endosperm.

Which of the following statements regarding flowering plants is correct?

Female gametophytes develop from megaspores within the anthers.

Many flowering plants coevolve with specific pollinators. The Madagascar orchid has a 12-inch floral tube and is a reliable nectar source for the hawkmoth, which has a correspondingly long proboscis (tongue). Which statement most accurately describes how coevolution might have occurred for the hawkmoth and Madagascar orchid?

Natural selection would favor orchids with nectar tubes just long enough to for an insect with pollen to make contact. Hawkmoths whose tongue could reach the deep tubes would be more fit.

Which of the following is one possible advantage of biofuels vs. oil?

The CO2 produced by biofuels will be absorbed by the crops used to produce them, creating a carbon-neutral cycle.

Cottonwood, aspen, and willow trees have beige flowers, with no petals, that appear before the tree's leaves are out in the spring; and they are dioecious. What does this indicate about these trees?

Their pollen is dispersed by wind.

A fruit is

a mature ovary.

Pineapple is a ________ fruit.

aggregate

Retaining the zygote on the living gametophyte of land plants _____.

allows it to be nourished by the parent plant

The term alternation of generations refers to the

alternation of gametophytes and sporophytes in the life cycle of plants.

Which of the following is correctly paired with its life cycle generation?

anther: sporophyte

Over human history, which process has been most important in improving the features of plants that have long been used by humans as staple foods?

artificial selection

The black dots that cover strawberries are actually individual fruits. The fleshy and tasty portion of a strawberry derives from the receptacle of a flower with many separate carpels. Therefore, a strawberry is

both an aggregrate fruit and an accessory fruit.

"Golden Rice" _____.

contains daffodil genes that increase vitamin A content

While looking at a flower in your garden, you notice that it has carpels with very long styles, and stamens with very short filaments. This plant is most likely to reproduce by ________.

cross-pollination

The germination of seeds _____.

depends on imbibition

Which association below is correct?

dioecious ... separate female and male plants

In which of the following pairs are the two terms equivalent?

embryo sac - female gametophyte

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

enhanced survival of genetically favorable offspring

Two unique reproductive adaptations of angiosperms are

flowers and fruits.

Which of the following is an example of sexual reproduction?

fusion of sperm and egg nuclei in an ovule

The term transgenes refers to

genes that are transferred from the genome of one organism into another.

Regardless of where in the world a vineyard is located, for the winery to produce a Burgundy, it must use varietal grapes that originated in Burgundy, France. The most effective way for a new California grower to plant a vineyard to produce Burgundy is to _____.

graft varietal Burgundy grape scions onto native (Californian) root stocks

Self-incompatibility _____.

helps maintain genetic variability in a population

"Bt maize"

includes bacterial genes that produce a toxin that reduces damage from insect pests.

Which of the following could be considered an evolutionary advantage of asexual reproduction in plants?

increased success of progeny in a stable environment

The generative cell of male angiosperm gametophytes is haploid. This cell divides to produce two haploid sperm cells. What type of cell division does the generative cell undergo to produce these sperm cells?

mitosis

During the alternation of generations in plants, _____.

mitosis produces gametes

Plants produce more seeds when they reproduce asexually than sexually. Yet most plants reproduce sexually in nature. What is the probable explanation for the prevalence of sexual reproduction? Sexual reproduction ________.

mixes up alleles, contributing to variation in a species

Double fertilization means that _____.

one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei

Double fertilization means that

one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei.

Which of the following flower parts develops into the pulp of a fleshy fruit?

ovary

Plant biotechnology is an effective tool for ________.

reducing world hunger

Which of the following is the correct order of floral organs from the outside to the inside of a complete flower?

sepals → petals → stamens → carpels

Before plowing a field, a farmer thought the bare field looked weed-free. Three days after plowing and turning over the soil, he was amazed to see thousands of tiny seedlings. What is the most likely reason for the mass germination of seeds?

small seeds that need light to germinate

Which of the following would be the most problematic for the natural environment in the development of genetically engineered crops?

the creation of transgenic crops that hybridize more easily

Which of these is a major trend in land plant evolution?

the trend toward a sporophyte-dominated life cycle

A small flower with green petals is most likely

wind-pollinated.