CLEP - Biology Plant Reproduction and Structure Questions and Answers — Questions and Answers
Question 1: In angiosperms, which of the following structures is the female reproductive organ that contains the ovules?
- Stamen
- Petal
- Sepal
- Pistil (Correct answer)
Correct answer: Pistil
The pistil, also known as the carpel, is the female reproductive part of a flower. It consists of the stigma (receives pollen), style (connects stigma to ovary), and the ovary, which houses the ovules that develop into seeds after fertilization.
Question 2: Which of the following statements accurately describes the process of double fertilization in flowering plants?
- Two sperm nuclei fertilize two separate eggs, resulting in twin embryos.
- One sperm nucleus fertilizes the egg to form the zygote, and the other fuses with the two polar nuclei to form the endosperm. (Correct answer)
- A single sperm nucleus divides within the ovule to fertilize both the egg and a polar nucleus.
- Two pollen grains are required to land on the stigma to fertilize the egg and the central cell separately.
Correct answer: One sperm nucleus fertilizes the egg to form the zygote, and the other fuses with the two polar nuclei to form the endosperm.
Double fertilization is a unique process in angiosperms where two fertilization events occur. One sperm nucleus from the pollen tube fuses with the egg cell to form the diploid (2n) zygote, which becomes the embryo. The second sperm nucleus fuses with the two polar nuclei in the central cell to form a triploid (3n) cell, which develops into the endosperm, a nutritive tissue for the embryo.
Question 3: In the life cycle of a fern, which of the following structures represents the dominant, diploid (2n) sporophyte generation?
- The prothallus
- A spore
- The archegonium
- The mature frond (Correct answer)
Correct answer: The mature frond
The large, leafy plant that is commonly recognized as a fern is the diploid (2n) sporophyte. This is the dominant generation in the fern life cycle. The prothallus is the small, haploid (n) gametophyte; a spore is a haploid (n) reproductive cell that grows into the gametophyte; and the archegonium is the egg-producing organ on the haploid gametophyte.
Question 4: A botanist examining a plant stem cross-section observes vascular tissue composed of non-living cells forming continuous tubes. This tissue is found to be responsible for the bulk flow of water and dissolved minerals from the roots. Which tissue is being observed?
- Phloem
- Xylem (Correct answer)
- Epidermis
- Parenchyma
Correct answer: Xylem
Xylem is the vascular tissue responsible for transporting water and minerals from the roots to the rest of the plant. It is composed of cells (tracheids and vessel elements) that are dead at maturity, forming hollow tubes ideal for the bulk flow of water. Phloem transports sugars, the epidermis is the outer protective layer, and parenchyma is a ground tissue with various functions.
Question 5: A plant species produces seeds that are lightweight and possess large, feathery structures. These adaptations are most characteristic of which primary mode of seed dispersal?
- Dispersal by animals (zoochory)
- Dispersal by water (hydrochory)
- Dispersal by wind (anemochory) (Correct answer)
- Mechanical self-dispersal (autochory)
Correct answer: Dispersal by wind (anemochory)
Features such as being lightweight and having feathery or wing-like structures increase the seed's surface area and buoyancy in the air, allowing it to be carried over long distances by air currents. This method of dispersal is known as anemochory, or wind dispersal.
Question 6: A houseplant on a windowsill bends towards the light. This directional growth, known as phototropism, is primarily caused by the unequal distribution of which plant hormone?
- Gibberellin
- Ethylene
- Auxin (Correct answer)
- Abscisic acid
Correct answer: Auxin
Phototropism is mediated by the plant hormone auxin. Light causes auxin to migrate from the illuminated side to the shaded side of the stem tip. The higher concentration of auxin on the shaded side stimulates greater cell elongation there, causing the stem to bend and grow towards the light source.
CLEP - Biology Plant Reproduction and Structure Questions and Answers
In angiosperms, which of the following structures is the female reproductive organ that contains the ovules?