Question 1

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

Accepted Answer

The lack of petals on the flowers and the timing of their appearance before the leaves suggest that these trees rely on wind for pollination, rather than attract pollinators with colourful petals.

Question 2

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

Accepted Answer

The long styles and short filaments suggest that this plant has adaptations for cross-pollination, as the long styles increase the distance between the stigma and the anthers, reducing the chances of self-pollination. The short filaments suggest that the plant relies on external pollinators to transfer pollen between flowers. Asexually reproducing plants would not have flowers or reproductive structures such as carpels and stamens. Selfing, or self-fertilization, is possible in plants with both male and female reproductive structures in the same flower, but the long styles suggest that this plant is adapted for cross-pollination, making selfing less likely.

Question 3

Which of the following is another name for the female gametophyte?

Accepted Answer

The female gametophyte is also known as the embryo sac. It is the structure within the ovule that contains the egg cell and other cells that play a role in fertilization and embryonic development. The polar nuclei, carpel, and megaspores are all different structures or cells involved in the development of the female reproductive system, but they do not specifically refer to the female gametophyte.

Question 4

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

Accepted Answer

For each ovule to develop into a mature seed, it must be fertilized by a pollen grain. Therefore, a minimum of 50 pollen grains must land on the stigma to fertilize the 50 ovules.

Question 5

Which theory have biologists associated with the occurrence of pollination syndrome?

Accepted Answer

Pollination syndrome is a type of coevolution where the characteristics of a flower and its pollinator have evolved together in response to each other. This means that the flower has adapted its traits to attract a specific type of pollinator, while the pollinator has adapted its traits to efficiently gather nectar or pollen from that type of flower.

Question 6

What is not true about the carpel of a flower?

Accepted Answer

Meiosis of the megaspore does not form the eight nuclei of the embryo sac. Instead, meiosis of the megaspore forms four haploid cells, one of which develops into the embryo sac through mitotic divisions.

Question 7

Most plants are adept at asexual reproduction. What is the probable explanation for the energy spent for sexual reproduction?

Accepted Answer

Sexual reproduction mixes up genes, contributing to variation in a species. This variation allows for genetic diversity, which can be advantageous for a species in changing environments and provides a greater likelihood of survival for offspring. While asexual reproduction may produce robust clones, the lack of variation leaves the species vulnerable to environmental changes and disease. Therefore, the energy spent on sexual reproduction is often worth it for the long-term survival and success of a species.

Question 8

It is estimated that animal- or insect- pollinated plants produce 1000 pollen grains for each ovule; wind- pollinated plants produce 1,000,000 pollen grains for each ovule. What does that indicate about pollination systems?

Accepted Answer

The fact that wind-pollinated plants produce a much higher amount of pollen for each ovule compared to animal-pollinated plants indicates that wind pollination is less efficient than animal-assisted pollination. This is because wind pollination relies on a much larger amount of pollen to increase the chances of successful pollination since the pollen is simply carried by the wind and has a lower chance of reaching its intended target. In contrast, animal-assisted pollination is more targeted and efficient, requiring fewer pollen grains to achieve successful pollination.

Question 9

How are the life cycles of liverworts and angiosperms alike?

Accepted Answer

In both liverworts and angiosperms, the sporophyte generation produces spores, which is a key feature of their life cycles. This is a fundamental aspect of the reproductive cycle in plants where the sporophyte phase follows the gametophyte phase.

Question 10

A summer occupation in the Corn Belt states is de- tasseling the corn: removing unwanted male flowers so that female flowers on the same plant are pollinated by the desired pollen for the hybrid corn. What does this tell you about corn?

Accepted Answer

Corn is a monoecious plant, which means that it has both male and female flowers on the same plant. However, the male flowers are located on the tassel at the top of the plant, while the female flowers are located in the ear or cob of the plant. Therefore, in order to ensure that the female flowers are pollinated by the desired pollen, the male flowers on the tassel must be removed through a process called de-tasseling.

Question 11

The sperm and egg each contribute 50% of the nuclear genetic material to the zygote that becomes the embryo and the new plant. Mitochondria and plastids that become chloroplasts are passed primarily from the female parent. What feature of the male or female gametophytes accounts for this?

Accepted Answer

The female gametophyte, or embryo sac, is formed from one surviving megaspore and is therefore larger and more complex than the male gametophyte, or pollen grain. This allows for the accumulation of cytoplasm and organelles, such as mitochondria and plastids, which are primarily passed down from the female parent to the offspring.

Question 12

Angiosperms are unique in having double fertilization that forms endosperm. What is true about double fertilization in angiosperms?

Accepted Answer

In angiosperms, one sperm combines with the egg to form the zygote, and the other sperm combines with the polar nuclei to form endosperm. This is known as double fertilization, and it is unique to angiosperms. The endosperm serves as a source of nutrients for the developing embryo.

Question 13

During self- fertilization, which of the following is absent?

Accepted Answer

Self-fertilization involves the transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant, not between different plants.

Question 14

What is an essential part of alternation of generations in plants?

Accepted Answer

In the alternation of generations, mitosis is used to produce gametes in the gametophyte stage.

Question 15

What is the similarity between spores and gametes?

Accepted Answer

Both spores and gametes are haploid, meaning they contain a single set of chromosomes.

Question 16

A population of flowers varies from deep blue to nearly white. Bees are active during the day and prefer colour. Moths are active at night, when colours are not very visible and white is more conspicuous. Design a scenario in which the blue and white flowers form two species where there once was one species. You must end with a conclusion that the two new species cannot interbreed a definition of a species).

Accepted Answer

The answer of A population of flowers varies from deep...

Question 17

Within which structure does meiosis and spore production occur?

Accepted Answer

Meiosis and spore production occur within sporangia, which are structures that produce and contain spores in plants and fungi.

Question 18

Which of the following correctly identifies the function of the flower part named?

Accepted Answer

Sepals are the outermost part of the flower and protect the bud before it blooms. Petals are typically the brightly colored, inner part of the flower that attract pollinators. The carpel is the female reproductive structure that contains the ovule, which will eventually develop into the seed. The stigma is the part of the carpel that receives the pollen from the male reproductive structures of other flowers.

Question 19

Male gametophytes are derived from which of the following via mitosis?

Accepted Answer

Male gametophytes are derived from microspores via mitosis. Microspores undergo mitotic division to form pollen grains, which are the male gametophytes in seed plants.

Question 20

What is the male gametophyte made of?

Accepted Answer

The male gametophyte, also known as pollen, is made up of a generative cell and a tube cell. The generative cell divides to produce two sperm cells, which fertilize the egg cells in the female gametophyte, while the tube cell forms a pollen tube that delivers the sperm cells to the female gametophyte.

Quiz 38: Plant Reproduction and Development