AP Biology : Plant Biology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Understanding Plant Reproduction

Double fertilization in angiosperms results in a __________ zygote and a triploid __________.

Possible Answers:

diploid . . . fruit

diploid . . . seed

haploid . . . endosperm

diploid . . . endosperm

haploid . . . fruit

Correct answer:

diploid . . . endosperm

Explanation:

Double fertilization is the process by which two sperm cells are introduced to the ovule. One sperm () fertilizes the egg (), creating a zygote(). The other sperm combines with the two polar nuclei (), forming the endosperm () that will nourish the embryo.

Example Question #2 : Plant Functions

Which of the following is true of the sporophyte of a plant?

Possible Answers:

It produces spores, which grow into gametophytes

It produce seeds, which grow into gametophytes

It produce zygotes, which grow into gametophytes

It produce zygotes, which grow into sporophytes

None of these

Correct answer:

It produces spores, which grow into gametophytes

Explanation:

The sporophyte produces spores, which grow into gametophytes. The gametophyte produces both ovules and pollen, which unite to form a zygote. The zygote grows into the next sporophyte. The plant life cycle continues to alternate between these stages. In flowering plants, the gametophyte stage has been greatly reduced compared to the sporophyte stage.

Example Question #2 : Understanding Plant Reproduction

Pollination is a process in which pollen is transferred between which of the following two structures of an angiosperm?

Possible Answers:

From the anther to the stigma

From the pollen tube to the ovary 

From the stamen to the ovary 

From the stigma to the anther

Correct answer:

From the anther to the stigma

Explanation:

Pollination is the process in angiosperms through which pollen is transferred from the male anther to the female stigma. Pollination can be either abiotic (i.e. by the wind) or biotic (i.e. by an animal). This process precedes fertilization.

Example Question #1181 : Ap Biology

Which of the following can be best described as a method of pollination?

Possible Answers:

All of these

Another organism

Water

Wind

Correct answer:

All of these

Explanation:

Pollination is defined as the transfer of pollen from the male anther to the female stigma of an angiosperm. There are abiotic and biotic methods of pollinations. Abiotic pollination includes wind and water while in biotic pollination another organism facilitates pollination.

Example Question #1182 : Ap Biology

Diecious plants (such as Gingko biloba) have separate sexes rather than having both male and female parts on a single plant.

Given that ginkgo is diecious, which plants would you expect to produce pollen?

Possible Answers:

Both male and female gingko plants

All male gingko plants and some female gingko plants

Only male gingko plants

Only female gingko plants

Niether; diecious plants do not produce pollen

Correct answer:

Only male gingko plants

Explanation:

Pollen is the male part of the plant, and thus is only produced by male ginkgo plants. Females have ovules with a fleshy, fruit-like outer layer and rely on the males plants for pollination. (Ginkgo is a gymnosperm and thus technically not a flowering/fruit-producing plant.)

Example Question #73 : Plant Biology

Which of the following techniques could be used to determine if a species of plant requires potassium?

Possible Answers:

Measure how fast radioactive potassium enters the plant

Grow a sample of plants in a potassium-rich environment and another sample in a potassium-deprived environment

Use autoradiography to find potassium in leaf tissues

Measure the amount of potassium in a sample of plants

Analyze root contents for potassium

Correct answer:

Grow a sample of plants in a potassium-rich environment and another sample in a potassium-deprived environment

Explanation:

In hypothesis-based scientific inquiry, the experiment must have an experimental group and a control group. In this case, growing plants with potassium would be the experimental group and growing plants without potassium would be the control group. Maintaining all other experimental variables, this method would allow the researcher to determine whether the plant species requires potassium. If the plants in the potassium-deprived environment die, but the plants in the potassium-rich environment survive, we can conclude that potassium is necessary for this species to survive.

The presence of potassium in the plant, leaves, or roots does not indicate it is a required nutrient. This simply indicates that the plant is capable of absorbing potassium, but does not show a dependency on potassium. Also, the movement of potassium into the plant does not indicate it is a required nutrient.

Example Question #1 : Understanding Other Plant Functions

Which of the following nutrients is most likely to be abundant in soil? 

Possible Answers:

Phosphorus

Hydrogen

Oxygen

Carbon

Iron

Correct answer:

Iron

Explanation:

There are many necessary nutrients involved in plant development. The nutrients are used in different quantities and are grouped accordingly in two categories: micronutrients and macronutrients. Micronutrients, such as iron, are important to healthy plant growth but are used in small quantities. Macronutrients, such as oxygen, carbon, hydrogen, and phosphorus, are also used for healthy plant growth but are used in the greatest quantities.

As a result, the macronutrients are more likely to become depleted in the soil as the plant absorbs them, while the micronutrients remain abundant. Iron, as a micronutrient, is more likely to be abundant in soil than any of the macronutrients.

Example Question #1 : Plant Reproduction

Perishable fruit is often picked before it is ripe. This hard, unripe fruit is easier to transport as it is less likely to bruise or spoil while in transit. Once fruit reaches its destination, it can be sprayed with a plant hormone that will promote its rapid ripening. What hormone is most likely used for this function?

Possible Answers:

Abscisic acid (ABA)

Cytokinins

Gibberellins

Ethylene

Correct answer:

Ethylene

Explanation:

Ethylene gas promotes fruit ripening; in a classic example of a positive feedback loop, ripe fruit causes the production of more ethylene gas, which promotes more fruit ripening (this is the origin of the phrase "one bad apple spoils the bunch!")

Cytokinins stimulate cell division and cytokinesis, and they can delay senescence (deterioration due to age, as in the case of cells). Gibberellins promote cell growth, and also promote stem and leaf elongation. Abscisic acid (ABA) promotes seed dormancy, inhibits plant growth, and closes plant stomata during water shortages. 

Example Question #71 : Plant Biology

Which of the following is not true of auxins, a class of plant hormones?

Possible Answers:

They enhance apical dominance, which promotes plants' upward growth, as opposed to lateral growth

They are responsible for phototropism—plants' tendency to grow toward light sources

They promote fruit ripening, which triggers the production of more auxins

Indoleacetic acid (IAA) is a natural auxin

Correct answer:

They promote fruit ripening, which triggers the production of more auxins

Explanation:

Auxins play a number of crucial roles in plant growth, behavior, and development. They were the first major class of plant hormone to be discovered and are present in all parts of a plant in varying concentrations. Some of their more notable functions include causing phototropism, enhancing apical dominance, and softening the cell wall to stimulate cell elongation and growth. Indoleacetic acid (IAA) is a naturally occurring auxin, though some synthetic auxins are used as weed killers.

Ethylene gas is a plant hormone that promotes fruit ripening in a positive feedback loop. Ripe fruit produces more ethylene gas, which promotes more fruit ripening, and so on. It is not a kind of auxin.

Example Question #72 : Plant Biology

What is the function of lateral meristems?

Possible Answers:

Stimulate root hair growth

Maintain water homeostasis

Provide nutrients to apical meristems

Provide secondary growth in woody plants

Correct answer:

Provide secondary growth in woody plants

Explanation:

In addition to growing in height, woody plants also grow in thickness. This is the function of lateral meristems. Lateral meristems are comprised of the vascular cambrium, and by cork cambrium that form vascular cylinders. The vascular cambrium adds layers of secondary xylem and phloem (wood), whereas the cork cambrium replaces the outer epidermis with a thicker and tougher layer called periderm.

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