SAT - Biology Subject Plant Structure and Function Questions and Answers

Question 1

The upward movement of water through the xylem in a 30-meter tall oak tree is best explained by which of the following?

Accepted Answer

The cohesion of water molecules and the tension created by transpiration.

Answer

The continuous pumping action of specialized cells in the roots.

Answer

The high pressure potential generated in the leaves.

Answer

The active transport of water molecules across xylem cell membranes.

Question 2

A houseplant placed on a windowsill bends towards the light. This phenomenon, known as phototropism, is primarily mediated by the redistribution of which plant hormone?

Accepted Answer

Auxin

Answer

Gibberellin

Answer

Ethylene

Answer

Cytokinin

Question 3

Which statement accurately compares the functions of xylem and phloem?

Accepted Answer

Xylem primarily transports water and minerals from the roots up, while phloem transports sugars from sources to sinks.

Answer

Xylem transports sugars bidirectionally, while phloem transports water unidirectionally.

Answer

Xylem is composed of living sieve-tube elements, while phloem is composed of dead vessel elements.

Answer

Xylem provides flexible support, while phloem provides the main rigid structure of the stem.

Question 4

The Casparian strip in the root endodermis is a critical structure for selective nutrient uptake because it:

Accepted Answer

forces water and solutes to pass through the selectively permeable membrane of endodermal cells.

Answer

stores excess minerals and water for the plant.

Answer

increases the surface area available for the apoplastic pathway.

Answer

produces hormones that regulate mineral absorption.

Question 5

Double fertilization, a process unique to angiosperms, involves the fusion of two sperm nuclei with which female gametophyte cells?

Accepted Answer

One sperm with the egg cell, and the other with the two polar nuclei in the central cell.

Answer

Both sperm with the egg cell to create a triploid zygote.

Answer

One sperm with a synergid cell, and the other with the egg cell.

Answer

One sperm with an antipodal cell, and the other with the central cell.

Question 6

During a period of prolonged drought, a plant's stomata will close to conserve water. What is the most significant trade-off of this physiological response?

Accepted Answer

A reduced intake of carbon dioxide, limiting photosynthesis.

Answer

An increase in the rate of transpiration, leading to wilting.

Answer

An inability to release excess oxygen, causing cellular damage.

Answer

A halt in the transport of water through the xylem.