Deck 34: Leaf Structure and Function

Question 1

Figure 34-1 The leaf arrangement illustrated in the accompanying figure is:

A) pinnate.
B) alternate.
C) compound.
D) whorled.
E) parallel.

Answer 1

B

Question 2

The broad, flat part of a leaf is called the ____, while the stalk that attaches the leaf to the stem is called the ____.

A) stipule; petiole
B) blade; stipule
C) stipule; axil
D) petiole; axil
E) blade; petiole

Answer 2

E

Question 3

Figure 34-2 In the accompanying figure, the palisade mesophyll is labeled with the number:

A) 1
B) 2
C) 3
D) 6
E) 9

Answer 3

A

Question 4

Guard cells are often associated with ____, special epidermal cells that provide a reservoir of water and ions.

A) companion cells
B) cuticle cells
C) cork cells
D) sclerenchyma cells
E) subsidiary cells

Question 5

Mesophyll cells are:

A) arranged tightly together.
B) separated by intercellular spaces.
C) responsible for the opening and closing of stomata.
D) devoid of chloroplasts.
E) covered by a waxy cuticle, which they secrete.

Question 6

The area of the angle between the stem and the petiole is referred to as the:

A) axil.
B) blade.
C) petiole.
D) stipule.
E) trichome.

Question 7

Leaves:

A) represent a fairly small fraction of the overall metabolic budget for a plant.
B) depend on the roots to supply CO₂.
C) are the main photosynthetic organ of most plants.
D) are the main site of water uptake in plants.
E) prevent CO₂ and O₂ from entering the plant.

Question 8

Stomata are:

A) waxy layers that cover leaves.
B) openings in the leaf epidermis.
C) extensions of bundle sheaths.
D) particularly numerous on the upper epidermis.
E) guarded by two stipule cells.

Question 9

Trichomes on plants are responsible for:

A) preventing water absorption on leaf surfaces.
B) deterring herbivores.
C) absorbing salts absorbed from the air.
D) the waxy structures on the petiole.
E) facilitating gas exchange.

Question 10

Floating leaves of aquatic plants have:

A) stomata only on the lower epidermis.
B) stomata only on the upper epidermis.
C) stomata on both the lower and upper epidermis.
D) no stomata on the epidermis.
E) stomata only within the mesophyll.

Question 11

Photosynthesis occurs mainly in the leaf's:

A) subsidiary cells.
B) bundle sheath extensions.
C) palisade mesophyll.
D) trichomes.
E) vascular bundles.

Question 12

Figure 34-2 Refer to the accompanying figure. The structure labeled with the number ____ is responsible for the transport of dissolved sugars.

A) 4
B) 5
C) 6
D) 7
E) 9

Question 13

Usually the only epidermal cells with chloroplasts are:

A) stomata.
B) stoma.
C) parenchyma.
D) guard cells.
E) all of these.

Question 14

Leaflike outgrowths at the base of the leaf stalk are referred to as:

A) axils.
B) blades.
C) lamina.
D) petioles.
E) stipules.

Question 15

Which statement describes the leaf epidermis?

A) Its cells lack chloroplasts.
B) Some of its cells perform photosynthesis.
C) Its cell walls are thin.
D) Its cells are opaque.
E) It has only a single layer.

Question 16

Figure 34-1 The type of leaf arrangement in the accompanying figure is characteristic of:

A) ashes.
B) maples.
C) catalpas.
D) beeches.
E) buckeyes.

Question 17

Compound leaves have:

A) parallel veins instead of netted veins.
B) alternate leaf attachment instead of opposite leaf attachment.
C) palmately netted leaves instead of pinnately netted leaves.
D) two or more leaflets instead of a single blade.
E) many leaves per plant instead of a single leaf per plant.

Question 18

The middle portion of a leaf that is sandwiched between the upper and lower epidermis is called the:

A) mesoderm.
B) middle lamella.
C) mesophyte.
D) bundle sheath.
E) mesophyll.

Question 19

Figure 34-2 The organization of tissues in the accompanying figure is characteristic of a:

A) stem.
B) spine.
C) leaf blade.
D) petiole.
E) bud scale.

Question 20

The cuticle consists of:

A) cellulose.
B) lignin.
C) hemicellulose.
D) starch.
E) cutin.

Question 21

Which of the following is true of monocot leaves?

A) Many monocots have a distinct palisade layer.
B) Many monocots lack a petiole.
C) Many monocots have a distinct spongy layer.
D) Many monocot leaves are broad.
E) Many monocot leaves have netted venation.

Question 22

Before a stoma opens, ____.

A) the level of carbon dioxide inside the leaf increases
B) potassium ions are actively transported out of guard cells
C) potassium ions are actively transported into guard cells
D) the turgor pressure inside the guard cells decreases
E) water moves by osmosis out of the guard cells

Question 23

Epidermal cells secrete a ____ to reduce water loss.

A) trichome
B) cuticle
C) oily substance
D) upper epidermis
E) stipules

Question 24

Monocot leaves typically have:

A) alternately palmate venation.
B) netted venation.
C) parallel venation.
D) alternately pinnate venation.
E) no venation.

Question 25

Eudicot leaves typically have:

A) alternately palmate venation.
B) netted venation.
C) parallel venation.
D) alternately pinnate venation.
E) no venation.

Question 26

The rate of transpiration decreases under which of the following conditions?

A) increased wind
B) increased humidity
C) increased temperature
D) presence of sunlight
E) an increase in dry air

Question 27

____ light triggers stomatal opening.

A) Red
B) Blue
C) Orange
D) Green
E) Yellow

Question 28

The process of photosynthesis involves the conversion of:

A) oxygen and water into sugar.
B) sugar into starches and cellulose.
C) oxygen and sugar into water.
D) carbon dioxide and water into sugar.
E) sugar and water into lipids.

Question 29

Photosynthesis reduces the leaf's internal concentration of:

A) hydrogen.
B) carbon dioxide.
C) nitrogen.
D) oxygen.
E) sugars and starches.

Question 30

After light triggers the activation proton pumps, what happens next in the leaf?

A) Chloride ions are pumped out of the guard cells.
B) Hydrogen ions are actively transported out of guard cells.
C) Potassium ions diffuse into guard cells.
D) Chloride ions diffuse out of guard cells.
E) Water moves by osmosis into guard cells.

Question 31

If a plant were placed in continual darkness, it would continue to open and close its stomata at approximately the same time each day. This phenomenon is governed by:

A) annual rhythms.
B) floral clocks.
C) transpiration.
D) temporal mechanisms.
E) circadian rhythms.

Question 32

Which change is most important in stomatal closing?

A) declining sucrose concentrations
B) rising sucrose concentrations
C) rising potassium concentrations
D) declining potassium concentrations
E) declining chloride concentrations

Question 33

Which structure or structures function to open and close the stomata?

A) cuticle
B) mesophyll
C) palisade cells
D) guard cells
E) chloroplasts

Question 34

The primary function of spongy mesophyll is:

A) photosynthesis.
B) transpiration.
C) to allow diffusion of gases.
D) transport of substances.
E) transport of water.

Question 35

The process by which water is lost by evaporation from aerial plant parts is known as:

A) vaporization.
B) photosynthesis.
C) guttation.
D) transpiration.
E) abscission.

Question 36

The needles of pines and other conifers are adapted to:

A) conserve water.
B) defend against herbivores.
C) reduce the effects of intense sunlight.
D) reduce the effects of snow and ice.
E) reduce the effects of wind.

Question 37

Guttation typically occurs:

A) at noon.
B) at dawn.
C) at dusk.
D) at night.
E) when the sun is at its peak.

Question 38

The stomatal opening and closing are under the control of ____.

A) ethylene
B) cytokinins
C) auxins
D) abscisic acid
E) gibberellins

Question 39

Opening and closing of the stomata:

A) occur during prolonged periods of drought.
B) occur when there is a high concentration of carbon dioxide in the leaf.
C) are under hormonal control.
D) are triggered by darkness.
E) are controlled by the changes in shape of the companion cells.

Question 40

During photosynthesis ____ diffuses into the leaf, while ____ diffuses out of the leaf.

A) carbon dioxide; oxygen
B) oxygen; carbon dioxide
C) oxygen; water vapor
D) water vapor; carbon dioxide
E) water vapor; oxygen

Question 41

Which event is associated with leaf abscission?

A) Chlorophyll breaks down.
B) Anthocyanins degrade.
C) Carotenoids are transported from the leaves.
D) Sugars accumulate in the leaves.
E) Leaves turn dark green.

Question 42

The area where the petiole detaches from the stem is referred to as the:

A) abscission zone.
B) middle lamella.
C) bundle sheath extension.
D) terminal bud.
E) bud scale scar.

Question 43

Parallel venation is characteristic of eudicot leaves.

Question 44

Identify three different types of modified leaves and list the function of each.

Question 45

One benefit of transpiration is that it:

A) concentrates nutrients in plant leaves.
B) distributes nutrients throughout the plant.
C) moves water from the atmosphere to the plant.
D) is responsible for warming plants.
E) brings in water from the soil.

Question 46

Compare the leaf structure of monocots and eudicots.

Question 47

Excess transpiration:

A) may be harmful to a plant.
B) causes an increase in turgor pressure.
C) is a synonym for precipitation.
D) occurs mainly in the winter.
E) is automatically counteracted by absorbing water from the soil.

Question 48

Underground stems with fleshy leaves used for storage of water and food are known as:

A) tendrils.
B) spines.
C) bulbs.
D) buds.
E) stipules.

Question 49

Subsidiary cells are the only epidermal cells that have chloroplasts.

Question 50

Modified leaves that protect meristematic tissue at the tips of woody plants are known as:

A) bulbs.
B) bud scales.
C) spines.
D) tendrils.
E) scale scars.

Question 51

Vines use ____ to stay attached to support structures.

A) spines
B) bracts
C) tendrils
D) needles
E) bulbs

Question 52

Leaf abscission:

A) occurs as a response to increased temperatures in temperate climates.
B) occurs as a response to dry conditions in tropical climates.
C) involves the formation of a tendril at the base of the petiole.
D) occurs year-round on deciduous plants.
E) does not occur in conifers.

Question 53

Leaf abscission is initiated and orchestrated by changing levels of the plant hormone ____.

A) ethylene
B) cytokinin
C) auxin
D) abscisic acid
E) gibberellin

Question 54

The spines of a cactus are actually modified:

A) branches.
B) stems.
C) leaves.
D) roots.
E) trichomes.

Question 55

Insectivorous plants:

A) typically grow in nutrient-rich soil.
B) enhance a poor supply of CO₂ through capturing prey.
C) use modified leaves to trap their prey.
D) require symbiotic insects and insect larvae to digest their prey.
E) require microorganisms to digest their prey.

Question 56

In cactus plants, the__________ is the main organ of photosynthesis.

A) leaf
B) spine
C) stem
D) flower
E) fruit

Question 57

The release of liquid water by leaves when soil moisture is high is known as:

A) vaporization.
B) photosynthesis.
C) guttation.
D) transpiration.
E) abscission.

Question 58

A(n) alternate leaf arrangement is one in which there is one leaf per node.

Question 59

A leaf without a(n) blade is said to be sessile.

Question 60

Identify and describe:
A. three different ways in which leaves can be arranged on stems, and list one example for each.
B. three different venation patterns in leaves and whether each is characteristic of eudicots or monocots.

Question 61

Transpiration increases at lower temperatures.

Question 63

Leaf abscission is initiated and orchestrated by the hormone abscisic acid .

Question 64

Stomata close as a result of water moving into guard cells.

Question 65

A cross section of a(n) monocot leaf typically shows veins in both cross-section and lengthwise section.

Question 66

A spine is a modified branch .

Question 67

Explain how the structure of a leaf contributes to the function of photosynthesis.

Question 70

The bundle sheath typically surrounds the larger veins .

Question 71

Palisade mesophyll is a tissue typically found on the side of the leaf toward the upper epidermis.

Question 72

Most transpiration occurs through stomata .

Question 73

Explain how the movement of hydrogen and potassium ions across the membranes of guard cells opens and closes the stomata.

Question 74

Describe the benefits of transpiration to plants.

Question 75

Red light has a wavelength that is the most effective for triggering stomatal opening.

Question 76

Guttation is the process most responsible for moving water and minerals through the plant.