Question 1

In plants, an increase in stomatal guard cell turgor is caused by

Accepted Answer

A)  the uptake of water via osmosis from surrounding cells. 
B)  the active transport of hydrogen ions into the cells. 
C)  the active transport of K+ and Cl- ions out of the cell. 
D)  the diffusion of K+ ions out of the cell. 
E)  an increase in guard cell water potential. 
A)  the uptake of water via osmosis from surrounding cells. 
B)  the active transport of hydrogen ions into the cells. 
C)  the active transport of K+ and Cl- ions out of the cell. 
D)  the diffusion of K+ ions out of the cell. 
E)  an increase in guard cell water potential.

Question 2

The water potential of a seedling was estimated to be -0.3 MPa. It was planted in saline soil with a water potential of -1.5 MPa. What would the seedling need to do in order to absorb water?

Accepted Answer

A)  Decrease its root cell water potential. 
B)  Increase its root cell water potential. 
C)  Actively secrete salts into the soil. 
D)  Actively take up salts at the leaves. 
E)  increase transpiration so there is increased evaporation, leading to increased water uptake. 
A)  Decrease its root cell water potential. 
B)  Increase its root cell water potential. 
C)  Actively secrete salts into the soil. 
D)  Actively take up salts at the leaves. 
E)  increase transpiration so there is increased evaporation, leading to increased water uptake.

Question 3

A loss of turgor is NOT associated with

Accepted Answer

A)  restricted photosynthesis. 
B)  increased pressure potential. 
C)  leaf wilting. 
D)  increased turgor pressure. 
E)  stomatal closure. 
A)  restricted photosynthesis. 
B)  increased pressure potential. 
C)  leaf wilting. 
D)  increased turgor pressure. 
E)  stomatal closure.

Question 4

In plants, the substances known as assimilates are

Accepted Answer

A)  the end products of photosynthesis. 
B)  transported from the roots to allow growth. 
C)  moved around the tree via xylem vessels. 
D)  root hormones. 
E)  amino acids. 
A)  the end products of photosynthesis. 
B)  transported from the roots to allow growth. 
C)  moved around the tree via xylem vessels. 
D)  root hormones. 
E)  amino acids.

Question 5

Arid plants that can minimise water loss and maximise the assimilation of CO2 would typically

Accepted Answer

A)  be able to have their stoma partially open during the day to conserve water without greatly reducing photosynthesis. 
B)  have their stoma open at midday, even in the hottest months of the year. 
C)  have leaves unresponsive to root signals relating to soil dryness. 
D)  not limit water loss at the expense of carbon gain. 
E)  not open their stoma during the day, but continue photosynthesis. 
A)  be able to have their stoma partially open during the day to conserve water without greatly reducing photosynthesis. 
B)  have their stoma open at midday, even in the hottest months of the year. 
C)  have leaves unresponsive to root signals relating to soil dryness. 
D)  not limit water loss at the expense of carbon gain. 
E)  not open their stoma during the day, but continue photosynthesis.

Question 6

Evolutionary modifications to the basic type of photosynthesis have enabled some plants to improve their water use efficiency. Which of the following statements is correct?

Accepted Answer

A)  C3 plants are able to photosynthesise effectively with very low levels of CO2. 
B)  Facultative CAM plants can switch from C3 to CAM photosynthesis as water becomes limiting. 
C)  CAM plants have very high levels of water use efficiency and high rates of photosynthesis. 
D)  C4 plants are rarely found in arid environments. 
E)  CAM plants use less water in the photosynthetic ATP production than do C3 plants. 
A)  C3 plants are able to photosynthesise effectively with very low levels of CO2. 
B)  Facultative CAM plants can switch from C3 to CAM photosynthesis as water becomes limiting. 
C)  CAM plants have very high levels of water use efficiency and high rates of photosynthesis. 
D)  C4 plants are rarely found in arid environments. 
E)  CAM plants use less water in the photosynthetic ATP production than do C3 plants.

Question 7

Osmotic adjustment in plants is a response to dry conditions and saline soils. This response involves plants

Accepted Answer

A)  actively moving water around to change turgor. 
B)  actively increasing water uptake rates from the soil. 
C)  increasing the amount of solutes in their vacuoles. 
D)  wilting in order to decrease cell water potential. 
E)  increasing the amount of water in their vacuoles. 
A)  actively moving water around to change turgor. 
B)  actively increasing water uptake rates from the soil. 
C)  increasing the amount of solutes in their vacuoles. 
D)  wilting in order to decrease cell water potential. 
E)  increasing the amount of water in their vacuoles.

Question 8

A plant is grown in the presence of carbon-14-labelled carbon dioxide. In an autoradiograph, you would NOT expect to find carbon-14-labelled assimilates in the

Accepted Answer

A)  roots. 
B)  young, expanding leaves. 
C)  fully expanded leaves. 
D)  shoot tips. 
E)  stomata. 
A)  roots. 
B)  young, expanding leaves. 
C)  fully expanded leaves. 
D)  shoot tips. 
E)  stomata.

Question 9

Water rises to the top of tall trees in the

Accepted Answer

A)  phloem via mass transport. 
B)  xylem due to cavitation. 
C)  xylem due to the cohesion of water molecules. 
D)  xylem due to root pressure. 
E)  xylem under positive hydrostatic pressure. 
A)  phloem via mass transport. 
B)  xylem due to cavitation. 
C)  xylem due to the cohesion of water molecules. 
D)  xylem due to root pressure. 
E)  xylem under positive hydrostatic pressure.

Question 10

In plants, ion movements in and out of stomatal guard cells are driven by

Accepted Answer

A)  electrons from the hydrolysis of water. 
B)  photons captured from light via Photosystem II. 
C)  proton pumping via membrane-bound ATPase. 
D)  osmotic gradients due to the presence of assimilates. 
E)  malate transport by PEP carboxylase. 
A)  electrons from the hydrolysis of water. 
B)  photons captured from light via Photosystem II. 
C)  proton pumping via membrane-bound ATPase. 
D)  osmotic gradients due to the presence of assimilates. 
E)  malate transport by PEP carboxylase.

Question 11

The symbiotic association between plants and mycorrhizal fungi increases plant growth rates by

Accepted Answer

A)  stimulating the growth of proteoid roots. 
B)  forming cluster roots which release exudates to solubilise phosphorous for uptake. 
C)  facilitating the conversion of gaseous nitrogen to organic nitrogenous compounds in root nodules. 
D)  enhancing the uptake of minerals from the soil. 
E)  increasing the rate of nutrient transport from roots to shoots. 
A)  stimulating the growth of proteoid roots. 
B)  forming cluster roots which release exudates to solubilise phosphorous for uptake. 
C)  facilitating the conversion of gaseous nitrogen to organic nitrogenous compounds in root nodules. 
D)  enhancing the uptake of minerals from the soil. 
E)  increasing the rate of nutrient transport from roots to shoots.

Question 12

Plants have many strategies for coping with drought conditions including

Accepted Answer

A)  being able to maintain cell turgor even at very low water potentials. 
B)  avoiding a dormant phase in the life cycle. 
C)  usually being able to withstand total dehydration. 
D)  maximising water loss and minimising CO2 assimilation. 
E)  having a small root system to survive low water potential. 
A)  being able to maintain cell turgor even at very low water potentials. 
B)  avoiding a dormant phase in the life cycle. 
C)  usually being able to withstand total dehydration. 
D)  maximising water loss and minimising CO2 assimilation. 
E)  having a small root system to survive low water potential.

Question 13

Which of the following statements about the effects of temperature on plant cells is correct?

Accepted Answer

A)  Extracellular ice formation may cause cell dehydration. 
B)  Plant cells are more likely to freeze than their extracellular fluid. 
C)  Very low temperatures have no effect on membrane fluidity. 
D)  Damage to plants at temperature extremes is due to decreased uptake of water. 
E)  High temperatures have no effect on enzyme shape and function. 
A)  Extracellular ice formation may cause cell dehydration. 
B)  Plant cells are more likely to freeze than their extracellular fluid. 
C)  Very low temperatures have no effect on membrane fluidity. 
D)  Damage to plants at temperature extremes is due to decreased uptake of water. 
E)  High temperatures have no effect on enzyme shape and function.

Question 14

Typically for plants

Accepted Answer

A)  water moves up a water potential gradient. 
B)  cytoplasmic solutes reduce the free energy of water. 
C)  the free energy of water molecules is less in soil than in cell cytoplasm. 
D)  the osmotic potential is lower in the xylem compared with that in leaf cells. 
E)  transpiration increases the water potential in xylem cells. 
A)  water moves up a water potential gradient. 
B)  cytoplasmic solutes reduce the free energy of water. 
C)  the free energy of water molecules is less in soil than in cell cytoplasm. 
D)  the osmotic potential is lower in the xylem compared with that in leaf cells. 
E)  transpiration increases the water potential in xylem cells.

Question 15

When a plant cell loses water and decreases in volume, the

Accepted Answer

A)  pressure potential and the osmotic potential both decrease. 
B)  pressure potential decreases but the osmotic potential increases. 
C)  water potential does not change. 
D)  water potential increases but the pressure potential decreases. 
E)  solute concentration decreases and osmotic potential increases. 
A)  pressure potential and the osmotic potential both decrease. 
B)  pressure potential decreases but the osmotic potential increases. 
C)  water potential does not change. 
D)  water potential increases but the pressure potential decreases. 
E)  solute concentration decreases and osmotic potential increases.

Question 16

In relation to the movement of assimilates in plants

Accepted Answer

A)  sources are always sites of photosynthesis. 
B)  sinks may import assimilates from storage reserves or from sites of photosynthesis. 
C)  sinks tend to be supplied equally by neighbouring and distant sources. 
D)  a structure cannot switch between being a source or a sink. 
E)  sources are always roots. 
A)  sources are always sites of photosynthesis. 
B)  sinks may import assimilates from storage reserves or from sites of photosynthesis. 
C)  sinks tend to be supplied equally by neighbouring and distant sources. 
D)  a structure cannot switch between being a source or a sink. 
E)  sources are always roots.

Question 17

During hot spells, why could drier conditions in the future lead to massive tree death?

Accepted Answer

A)  Leaf-drop due to water stress 
B)  Phloem collapse due to decreased turgor 
C)  More frequent embolisms and difficultly in recovering from them 
D)  Xylem collapse due to decreased turgor 
E)  All of the answers are correct 
A)  Leaf-drop due to water stress 
B)  Phloem collapse due to decreased turgor 
C)  More frequent embolisms and difficultly in recovering from them 
D)  Xylem collapse due to decreased turgor 
E)  All of the answers are correct

Question 18

Halophytes (salt-tolerant plants)

Accepted Answer

A)  are resistant to damage caused by wilting. 
B)  typically accumulate sufficient solutes to generate a cell water potential less than -6 MPa. 
C)  concentrate solutes in cell vacuoles to decrease cell water potential and prevent wilting. 
D)  accumulate water to generate a high osmotic pressure. 
E)  can accumulate organic solutes but not inorganic ions. 
A)  are resistant to damage caused by wilting. 
B)  typically accumulate sufficient solutes to generate a cell water potential less than -6 MPa. 
C)  concentrate solutes in cell vacuoles to decrease cell water potential and prevent wilting. 
D)  accumulate water to generate a high osmotic pressure. 
E)  can accumulate organic solutes but not inorganic ions.

Question 19

The apoplast in plants

Accepted Answer

A)  is the intracellular volume. 
B)  is a pore in the plasmodesmata. 
C)  contains the vacuole. 
D)  is the volume of the vacuole in the cell. 
E)  is the volume of the cell outside the plasma membrane. 
A)  is the intracellular volume. 
B)  is a pore in the plasmodesmata. 
C)  contains the vacuole. 
D)  is the volume of the vacuole in the cell. 
E)  is the volume of the cell outside the plasma membrane.

Question 20

Osmotic adjustment

Accepted Answer

A)  is a response of plants to lack of water where solute in the cell increases and the osmotic potential decreases. 
B)  is the capacity of a cell to retain water. 
C)  is the accumulation of cell vacuoles containing salt in halophytes. 
D)  only occurs in response to dry soil. 
E)  All of the answers are correct. 
A)  is a response of plants to lack of water where solute in the cell increases and the osmotic potential decreases. 
B)  is the capacity of a cell to retain water. 
C)  is the accumulation of cell vacuoles containing salt in halophytes. 
D)  only occurs in response to dry soil. 
E)  All of the answers are correct.

Exam 18: Plant Nutrition, Transport and Adaptation to Stress

In plants, an increase in stomatal guard cell turgor is caused by

The water potential of a seedling was estimated to be -0.3 MPa. It was planted in saline soil with a water potential of -1.5 MPa. What would the seedling need to do in order to absorb water?

A loss of turgor is NOT associated with

In plants, the substances known as assimilates are

Arid plants that can minimise water loss and maximise the assimilation of CO2 would typically

Evolutionary modifications to the basic type of photosynthesis have enabled some plants to improve their water use efficiency. Which of the following statements is correct?

Osmotic adjustment in plants is a response to dry conditions and saline soils. This response involves plants

A plant is grown in the presence of carbon-14-labelled carbon dioxide. In an autoradiograph, you would NOT expect to find carbon-14-labelled assimilates in the

Water rises to the top of tall trees in the

In plants, ion movements in and out of stomatal guard cells are driven by

The symbiotic association between plants and mycorrhizal fungi increases plant growth rates by

Plants have many strategies for coping with drought conditions including

Which of the following statements about the effects of temperature on plant cells is correct?

Typically for plants

When a plant cell loses water and decreases in volume, the

In relation to the movement of assimilates in plants

During hot spells, why could drier conditions in the future lead to massive tree death?

Halophytes (salt-tolerant plants)

The apoplast in plants

Osmotic adjustment

Nature of Molecules

Biomolecules

The Chemistry of Life

Functioning Cells

Movement Across Membranes

Harvesting Energy

Cells, Tissues and Signals

Cell Division

Inheritance

Genes, Chromosomes and Dna

The Genetic Code

Gene Expression

Genomes, Mutation and Cancer

Viruses

Genetic Engineering and Biotechnology

Reproduction, Growth and Development of Flowering Plants

Structure of Plants

Plant Hormones and Growth Responses

Animal Reproduction

Animal Development

Homeostasis: Water, Solutes and Excretion

Gas Exchange in Animals

Circulation

Metabolism, Temperature Regulation and Environmental Stress

Animal and Human Nutrition

Innate Defences and the Immune System

Hormonal Control in Animals

Nervous Systems

Animal Movement

Animal Behaviour

Evolving Life

Evolving Earth

Mechanisms of Evolution

Bacteria

The Protists

Plants

Fungi

Simple Animals: Sponges to Flatworms

Annelids, Molluscs, Nematodes and Arthropods

Echinoderms and Chordates

Australian Biota

Population Ecology

Living in Communities

Ecosystems

Human Impacts

Filters

Arid plants that can minimise water loss and maximise the assimilation of CO₂ would typically