A plant has the following characteristics: a taproot system, several growth rings evident in a cross section of the stem, and a layer of bark around the outside. Which of the following best describes the plant?
A) herbaceous eudicot
B) woody eudicot
C) woody monocot
D) herbaceous monocot

Answer: B

The following question are based on the drawing of root or stem cross sections shown in Figure 35.2.

Figure 35.2

A monocot stem is represented by
A) I only.
B) II only.
C) III only.
D) IV only.

Answer: B

Which of the following would be least likely to affect osmosis in plants?
A) proton pumps in the membrane
B) a difference in solute concentrations
C) receptor proteins in the membrane
D) aquaporins

Answer: C

Active transport of various materials in plants at the cellular level requires all of the following except
A) xylem membranes.
B) ATP.
C) membrane potential.
D) transport proteins

Answer: A

Compared to a cell with few aquaporins in its membrane, a cell containing many aquaporins will
A) have a faster rate of osmosis.
B) have a lower water potential.
C) have a higher water potential.
D) have a faster rate of active transport.

Answer: A

Which of the following is a correct statement about sugar movement in phloem?
A) Diffusion can account for the observed rates of transport.
B) Movement can occur both upward and downward in the plant.
C) Sugar is translocated from sinks to sources.
D) Only phloem cells with nuclei can perform sugar movement.

Answer: B

Which of the following soil minerals is most likely leached away during a hard rain?

A) Na+
B) K+
C) Ca++
D) NO₃-

Answer: D

Nitrogen fixation is a process that
A) recycles nitrogen compounds from dead and decaying materials.
B) converts ammonia to ammonium.
C) releases nitrate from the rock substrate.
D) converts nitrogen gas into ammonia.

Answer: D

A group of 10 tomato plants are germinated and maintained in a large tray with no drainage. After several weeks they all begin to wilt and die despite repeated watering and fertilization. The most likely cause of this die-off is
A) competition for resources.
B) anoxia.
C) organic nutrient depletion.
D) no room left for root growth.

Answer: B

Two groups of tomatoes were grown under laboratory conditions, one with humus added to the soil and one a control without humus. The leaves of the plants grown without humus were yellowish (less green) compared with those of the plants grown in humus-enriched soil. The best explanation for this difference is that
A) the healthy plants used the food in the decomposing leaves of the humus for energy to make chlorophyll.
B) the humus made the soil more loosely packed, so water penetrated more easily to the roots.
C) the humus contained minerals such as magnesium and iron, needed for the synthesis of chlorophyll.
D) the heat released by the decomposing leaves of the humus caused more rapid growth and chlorophyll synthesis.

Answer: C

Most of the dry mass of a plant is the result of uptake of ________.
A) water and minerals through root hairs
B) water and minerals through mycorrhizae
C) carbon dioxide through stomata in leaves
D) carbon dioxide and oxygen through stomata in leaves

Answer: C

Which of the following is the correct order of floral organs from the outside to the inside of a complete flower?
A) petals → sepals → stamens → carpels
B) sepals → stamens → petals → carpels
C) spores → gametes → zygote → embryo
D) sepals → petals → stamens → carpels

Answer: D

In which of the following pairs are the two terms equivalent?
A) ovuleegg
B) embryo sacfemale gametophyte
C) endospermmale gametophyte
D) seedzygote

Answer: B

Which of the following is a scientific concern related to creating genetically modified crops?
A) The nutritional quality of plants is reduced.
B) Genetically modified plants are less stable and may revert back to parental genotypes.
C) Genetically modified crops cannot survive without the addition of great amounts of fertilizer to the soil.
D) The introduction of novel organisms into the biosphere is unstoppable in nature.

Answer: D

Sperm cells are formed in plants by ________.
A) meiosis in pollen grains
B) meiosis in anthers
C) mitosis in male gametophyte
D) mitosis in the micropyle

Answer: C

The egg of a plant has a haploid chromosome number of 12 (n=12). What is true about the number of chromosomes in the cells of other tissues of this plant?
A) The leaves and stems have 12 chromosomes.
B) The zygote has 12 chromosomes.
C) The sperm has 6 chromosomes.
D) The endosperm has 36 chromosomes.

Answer: D

A student examining leaf cross sections under a microscope finds many loosely packed cells with relatively thin cell walls. The cells have numerous chloroplasts. What type of cells are they?
A) parenchyma
B) xylem
C) endodermis
D) collenchyma

Answer: A

When you eat beets, including sugar from sugar beets, what are you eating?
A) large axillary buds
B) storage roots
C) petioles
D) storage leaves

Answer: B

When you eat a celery stalk, what are you eating?
A) stems
B) roots
C) petioles
D) leaves

Answer: B

When you eat potatoes, what are you eating?
A) large axillary buds
B) stems
C) roots
D) leaves

Answer: B

CO₂ enters the inner spaces of the leaf through the
A) cuticle.
B) epidermal trichomes.
C) stoma.
D) phloem.

Answer: C

One important difference between the anatomy of roots and the anatomy of leaves is that
A) only leaves have phloem and only roots have xylem.
B) root cells have cell walls and leaf cells do not.
C) a waxy cuticle covers leaves but is absent from roots.
D) vascular tissue is found in roots but is absent from leaves.

Answer: C

Trichomes ________.
A) open and close for gas exchange
B) increase water loss from leaves
C) absorb sunlight, increasing the temperature of leaves
D) repel or trap insects

Answer: D

Which of the following are water-conducting cells that are dead at functional maturity?
A) tracheids and vessel elements
B) sieve-tube elements
C) collenchyma cells
D) parenchyma cells

Answer: A

(DIAGRAM) The main function associated with the thin top layer of a plant leaf is ________.
A) absorption of carbon dioxide
B) retention of water
C) release of carbon dioxide
D) collection of light

Answer: B

Plant meristematic cells ________.
A) increase the surface area of dermal tissue by developing root hairs
B) subdivide into three distinct cell types named parenchyma, ground meristem, and procambium
C) are distributed evenly in all tissues throughout the plant
D) are undifferentiated cells that produce new cells

Answer: D

The following question are based on the drawing of root or stem cross sections shown in Figure 35.2.

Figure 35.2

A woody eudicot is represented by
A) I only.
B) II only.
C) III only.
D) IV only.

Answer: D

What tissue makes up most of the wood of a tree?
A) primary xylem
B) secondary xylem
C) secondary phloem
D) mesophyll cells

Answer: B

Which of the following is true of bark?
A) It is composed of phloem plus periderm.
B) It has no identifiable function in trees.
C) It is formed by the apical meristems.
D) It forms annual rings in deciduous trees.

Answer: A

Root hairs are most important to a plant because they
A) anchor a plant in the soil.
B) store starches.
C) increase the surface area for absorption.
D) provide a habitat for nitrogen-fixing bacteria.

Answer: C

A plant developed a mineral deficiency after being treated with a fungicide. What is the most probable cause of the deficiency?
A) Mineral receptor proteins in the plant membrane were not functioning.
B) Mycorrhizal fungi were killed.
C) Active transport of minerals was inhibited.
D) The genes for the synthesis of transport proteins were destroyed.

Answer: B

What regulates the flow of water through the xylem?
A) active transport by tracheid and vessel elements
B) the number of companion cells in the phloem
C) the evaporation of water from the leaves
D) active transport by sieve-tube members

Answer: C

The ________ is the most efficient rout of water movement in plants, while the ________ is the most select.
A) apoplast; symplast
B) symblast; apoplast
C) apoplast; transmembrane
D) transmembrane; symplast

Answer: C

All of the following normally enter the plant through the roots except
A) carbon dioxide.
B) nitrogen.
C) potassium.
D) water.

Answer: A

Which of the following would be least likely to affect osmosis in plants?
A) proton pumps in the membrane
B) a difference in solute concentrations
C) receptor proteins in the membrane
D) aquaporins

Answer: C

In plant roots, the Casparian strip is correctly described by which of the following?
A) It aids in the uptake of nutrients.
B) It provides energy for the active transport of minerals into the stele from the cortex.
C) It ensures that all minerals are absorbed from the soil in equal amounts.
D) It ensures that all water and dissolved substances must pass through a cell membrane before entering the stele.

Answer: D

Most of the water taken up by a plant is
A) used as a solvent.
B) used as a hydrogen source in photosynthesis.
C) lost during transpiration.
D) converted to CO₂.

Answer: C

Which of the following is a similarity between xylem and phloem transport?
A) Bulk flow of water is involved.
B) Many cells in both tissues have sieve plates.
C) Transpiration is required for both processes.
D) Expenditure of energy from ATP is required.

Answer: A

Which of the following us not part of the transpiration-cohesion-tension mechanism for the ascent of xylem sap?
A) hydrophilic walls of tracheids and vessels that help maintain the column of water against gravity
B) loss of water from the mesophyll cells, which initiates a pull of water molecules from neighboring cells
C) active pumping of water into the xylem of roots
D) transfer or transpirational pull from one water molecule to the next, owing to cohesion by hydrogen bonds

Answer: C

Water potential is generally most negative in which of the following parts of a plant?
A) xylem vessels in roots
B) cells of the root cortex
C) mesophyll cells of the leaf
D) xylem vessels in leaves

Answer: C

Several tomato plants are growing in a small garden plot. If soil water potential were to drop significantly on a hot summer afternoon, which of the following would most likely occur?
A) The uptake of carbon dioxide would be enhanced.
B) Transpiration would increase.
C) The leaves would become more turgid.
D) Size of stomatal openings would decrease.

Answer: D

A group of 10 tomato plants are germinated and maintained in a large tray with no drainage. After several weeks they all begin to wilt and die despite repeated watering and fertilization. The most likely cause of this die-off is
A) a lack of oxygen for the roots
B) organic nutrient depletion
C) no room left for root growth
D) competition for resources

Answer: A

Which of the following soil minerals is most likely leached away during a hard rain?
A) Na+
B) K+
C) Ca++
D) NO₃-

Answer: D

Which of the following would inhibit the growth of most plants?
A) air spaces
B) abundant humus
C) good drainage
D) a pH above 10.0

Answer: D

Which of the following contributed to the dust bowl in the American southwest during the 1930s?
I) overgrazing by cattle.
II) plowing of native grasses.
III) lack of soil moisture

A) II and III
B) I, II and III
C) III
D) I and II

Answer: B

Which of the following would be the most effective strategy to remove toxic heavy metals from a soil?
A) heavy irrigation to leach out the heavy metals
B) application of fertilizers to compete with heavy metal uptake
C) application of sulfur to lower the soil pH and precipitate the heavy metals
D) adding plant species that have the ability to take up and volatilize heavy metals

Answer: D

Which criteria allow biologists to divide chemicals into macronutrients and micronutrients?
A) the quantities of each required by plants
B) molecular weight of the element or compound
C) whether or not they are essential for plant growth
D) how they are used in metabolism

Answer: A

Why is nitrogen fixation an essential process?
A) Nitrogen fixation can only be done by certain prokaryotes.
B) Fixed nitrogen is often the limiting factor in plant growth.
C) Nitrogen fixation is very expensive in terms of metabolic energy.
D) Nitrogen fixers are sometimes symbiotic with legumes.

Answer: B

You are weeding your garden when you accidentally expose some roots of your pea plants. You notice swellings (root nodules) on the roots and there is a reddish tinge to the ones you accidentally damaged. Most likely your peas plants
A) suffer from a mineral deficiency.
B) are infected with a parasite.
C) are benefiting from a mutualistic bacterium.
D) are developing offshoots from the root.

Answer: C

Which of the following is a primary difference between ectomycorrhizae and endomycorrhizae?
A) Endomycorrhizae have thicker, shorter hyphae than ectomycorrhizae.
B) Endomycorrhizae, but not ectomycorrhizae, form a dense sheath over the surface of the root.
C) Ectomycorrhizae do not penetrate root cells, whereas endomycorrhizae grow into invaginations of the root cell membranes.
D) Ectomycorrhizae are found in woody plant species; about 85% of plant families form ectomycorrhizae.

Answer: C

What major benefits do plants and mycorrhizal fungi receive from their symbiotic relationship?
A) Plants receive nitrogen and phosphorus, and fungi receive photosynthetic products.
B) Plants receive enzymes, and fungi receive nitrogen and phosphorus.
C) Fungi receive photosynthetic products in exchange for living in plant root nodules.
D) Plants receive increased root surface area, and fungi receive digestive enzymes.

Answer: A

Carnivorous plants have evolved mechanisms that trap and digest small animals. The products of this digestion are used to supplement the plant's supply of
A) energy.
B) carbohydrates.
C) lipids and steroids.
D) nitrogen and other minerals.

Answer: D

During the alternation of generations in plants, ________.
A) fertilization produces spores
B) mitosis produces gametes
C) meiosis produces gametes
D) fertilization produces gametes

Answer: B

Retaining the zygote on the living gametophyte of land plants ________.
A) helps in dispersal of the zygote
B) allows it to be nourished by the parent plant
C) evolved concurrently with pollen
D) protects the zygote from herbivores

Answer: B

Angiosperms are the most successful terrestrial plans. Which of the following features is unique to them and helps account for their success?
A) fruit enclosing seeds
B) wind pollination
C) sperm cells without flagella
D) dominant gametophytes

Answer: A

Which of the following is the correct order of floral organs from the outside to the inside of a complete flower?
A) petals → sepals → stamens → carpels
B) sepals → stamens → petals → carpels
C) spores → gametes → zygote → embryo
D) sepals → petals → stamens → carpels

Answer: D

Which of the following statements regarding flowering plants is correct?
A) The gametophyte is the dominant generation.
B) Female gametophytes develop from megaspores within the anthers.
C) Pollination is the delivery of pollen to the stigma of a carpel.
D) The food-storing endosperm is derived from the cell that contains two polar nuclei and one sperm nucleus.

Answer: C

Double fertilization means that ________.
A) flowers must be pollinated twice to yield fruits and seeds.
B) every egg must receive two sperm to produce an embryo.
C) one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei.
D) the egg of the embryo sac is diploid.

Answer: C

What is typically the result of double fertilization in angiosperms?
A) The endosperm develops into a diploid nutrient tissue.
B) A triploid zygote is formed.
C) Both a diploid embryo and triploid endosperm are formed.
D) Two embryos develop in every seed.

Answer: C

Which of the following flower parts develops into a seed?
A) ovary
B) ovule
C) carpel
D) stamen

Answer: B

Which of the following flower parts develops into the pulp of a fleshy fruit?
A) ovule
B) stigma
C) style
D) ovary

Answer: D

The vast number and variety of flower species is probably related to various kinds of ________.
A) seed dispersal agents
B) climatic conditions
C) herbivores
D) pollinators

Answer: D

Unripe fruits protect seeds from predation and early germination. What is the major function of ripe fruits?
A) releasing nutrients to seeds
B) attracting pollinators
C) dispersing seed
D) keeping the seed hydrated before germination

Answer: C

Which of the following could be considered an evolutionary advantage of asexual reproduction in plants?
A) increased success of progeny in a stable environment.
B) increased agricultural productivity in a rapidly changing environment.
C) maintenance and expansion of a large genome.
D) production of numerous progeny.

Answer: A

Which of the following is a scientific concern related to creating genetically modified crops?
A) Herbicide resistance may spread to weedy species.
B) Genetically modified crops cannot survive without the addition fo great amounts of fertilizer to the soil.
C) Genetically modified plants are less stable and may revert back to parental genotypes.
D) The monetary costs of growing genetically modified plants are significantly greater than traditional breeding techniques.

Answer: A

The detector of light during de-etiolation (greening) of a tomato plant is (are)
A) carotenoids.
B) xanthophylls.
C) phytochrome.
D) auxin

Answer: C

Which of these activities is part of the development of crop plants from wild relatives?
I) people planting seeds of the plants with the characteristic wanted
II) people making observations of desired plant characteristics
III) people eating products from only the plants with desired characteristics
IV) people developing several varieties of crops from a wild relative

A) I, II, and IV
B) I, III, and IV
C) I and IV
D) I and II

Answer: A

Genetically engineered plants ________.
A) include transgenic maize (corn) plants that can produce their own pesticides
B) are used in research but not yet in commercial agricultural production
C) are more difficult to develop than genetically engineered animals
D) are banned throughout the world

Answer: A

External stimuli would be received most quickly by a plant cell if the receptors for signal transduction were located in the
A) cell membrane.
B) cytoplasmic matrix.
C) endoplasmic reticulum.
D) nuclear membrane.

Answer: A

Plant hormonal regulation differs from animal hormonal regulation in that ________.
A) there are no dedicated hormone-producing organs in plants as there are in animals.
B) all production of hormones is local in plants with little long-distance transport.
C) plants do not exhibit feedback mechanisms like animals.
D) only animal hormone concentrations are developmentally regulated.

Answer: A

Which of the following plant growth responses is primarily due to the action of auxins?
A) leaf abscission
B) phototropism
C) cell division
D) the detection of photoperiod

Answer: B