Biology II - Chapter 36 Mastering

10a) Root hairs have which of the following roles in absorption and transport of water and minerals?

-Absorb the soil solution into the apoplast and symplast -Increase surface area of contact between the root epidermis and the soil solution Root hairs vastly increase the surface area of contact between root and soil, allowing for increased absorption of water and dissolved minerals into the apoplast and symplast of the root.

Transpiration provides the driving force for the movement of water from the soil to the highest leaves of plants. Transpiration is also linked to other processes in plants, including photosynthesis and the transport of mineral nutrients. Which of the following statements correctly describe(s) a relationship between transpiration and other processes in plants? -Water is pulled from the roots to the leaves by transpiration, whereas mineral nutrients diffuse from the roots to the leaves. -In most plants, the highest rate of transpiration occurs when the rate of photosynthesis is also highest. -The large surface area exposed to air inside the leaf maximizes the plant's ability to absorb CO2 while minimizing water loss through transpiration. -Transpiration is important in cooling leaves on warm, sunny days. -To minimize water loss during dry conditions, most plants must also restrict their ability to carry out photosynthesis. -Open stomata provide a low-resistance pathway for CO2 to enter and for water to exit the leaf.

-In most plants, the highest rate of transpiration occurs when the rate of photosynthesis is also highest. -Transpiration is important in cooling leaves on warm, sunny days. -Open stomata provide a low-resistance pathway for CO2 to enter and for water to exit the leaf. -To minimize water loss during dry conditions, most plants must also restrict their ability to carry out photosynthesis. Both water and CO2 diffuse as gases through stomata. Therefore, the opening of stomata to permit CO2 to rapidly enter the leaf also promotes water loss through transpiration. Conversely, when the stomata close to limit water loss under dry conditions, the entry of CO2 into the leaf is restricted and photosynthesis slows. Transpiration pulls both water and mineral nutrients from the roots to the leaves. It also cools the leaves as water evaporates from cell surfaces inside the leaves.

10b) Which of these statements about the Casparian strip is true?-It is hydrophobic -It prevents symplastic transport into the vascular cylinder -It is selectively permeable to water -It blocks apoplastic transport into the vascular cylinder -it is a waxy band of suberin around cells of the endodermis

-It is hydrophobic -It blocks apoplastic transport into the vascular cylinder -It is a waxy band of suberin around cells of the endodermis The Casparian strip is a waxy, hydrophobic band of suberin in the walls around the endodermal cells. It has the important job of blocking the apoplastic route of water and dissolved minerals.

10c) Water and dissolved minerals located in the cell walls and intercellular spaces of the root cortex are in the (1) _____ route of transport, and those in the cytoplasm of cortex cells are in the (2) _____ route. The (3) _____ route requires plasmodesmata. The (4) _____ route is obstructed by the Casparian strip, thereby forcing water and minerals to cross the plasma membranes of endodermal cells before gaining entrance into the vascular cylinder.

1- Apoplastic 2- Symplastic 3- Symplastic 4- Apoplastic The symplast and apoplast are the physical spaces in the plant body where water and dissolved minerals can flow. The symplast and apoplast are divided from each other by membranes.

20) Arrange the following five events in an order that explains the mass flow of materials in the phloem. 1. Water diffuses into the sieve tubes. 2. Leaf cells produce sugar by photosynthesis. 3. Solutes are actively transported into sieve tubes. 4. Sugar is transported from cell to cell in the leaf. 5. Sugar moves down the stem.

2, 4, 3, 1, 5

17) Ignoring all other factors, what kind of day would result in the fastest delivery of water and minerals to the leaves of an oak tree?

A very hot, dry, windy day

18c) Water follows a specific path as it moves from the xylem in the vein of a leaf to the air outside the leaf. Drag the labels into the flowchart to show the sequence of events after water enters a leaf in the xylem.

Because xylem cells lack cytoplasm, the xylem is part of the apoplast. Water moves via the apoplastic pathway from the xylem through the bundle sheath to all of the mesophyll cells of the leaf. From the mesophyll cell walls, water evaporates into the interior air spaces of the leaf. Finally, it exits the leaf as water vapor through the stomata.

8f) What characterizes the rates of photosynthesis and transport in a plant on a dry cloudy day?

Both the photosynthesis and transpiration rates are low. On a cloudy day with low soil moisture, the photosynthesis rate is low and stomata are closed, so the transpiration rate is low.

9c) In roots the _____ forces water and solutes to pass through the plasma membranes of _____ cells before entering the _____.

Casparian strip ... endodermis ... xylem The Casparian strip is a waterproof barrier that forces water and solutes to pass through the plasma membranes of endodermis cells.

8a) Which tissue acts as a filter on the water absorbed by root hairs? -Vascular tissue -Endodermis -Cortex -Epidermis

Endodermis Endodermal cells filter solutes from water and allow them to pass through to the vascular tissue.

8g) True or false? The rate of sugar transport in a plant depends on the rate of photosynthesis, the rate of transpiration, and the difference in turgor pressure between the source and the sink.

False While the rate of photosynthesis and the difference in turgor pressure between the source and the sink do influence the rate of sugar transport in the phloem, the rate of transpiration does not; transpiration mainly influences the rate of water transport through the xylem.

8b) True or false? Root pressure can move water a long distance up the xylem because of the higher water potential of the xylem in comparison to the water potential in the surrounding cells.

False, Root pressure can move water a short distance up the xylem because of the lower water potential of the xylem in comparison to the water potential in the surrounding cells.

9f) _____ cells are the cells that regulate the opening and closing of stomata, thus playing a role in regulating transpiration.

Guard Guard cells regulate the opening and closing of stomata.

10e) Some plant species are used for phytoremediation because when grown in soil contaminated by heavy metals and other pollutants, they accumulate the contaminants in their tissues. In this way, they can be used to clean up the soil. Such plants are called "hyper-accumulators." Other plants, however, cannot take up the contaminants from the soil and are called "non-accumulators."

Hyper-accumulators would have contaminants in the cortex and vascular cylinder, and non-accumulators would have contaminants in the cortex but not the vascular cylinder In order to be classified as a hyper-accumulator, a plant needs to be able to transport contaminants through the cortex and into the vascular cylinder so they can be sent up to the rest of the plant. Non-accumulators might have some contaminants in the cortex due to apoplast flow, but the plant would not take the contaminants up by active transport.

14) Which one of the following ions plays a critical role in the opening and closing of stomata? Which one of the following ions plays a critical role in the opening and closing of stomata? -Ca+ -2H+ -K+ -Na+

K+

6) A plant developed a mineral deficiency after being treated with a fungicide. What is the most probable cause of the deficiency?

Mycorrhizal fungi were killed.

9b) Which of these are symbiotic associations? Which of these are symbiotic associations? -Casparian strips -mycorrhizae -root hairs -symplast -apoplasts

Mycorrhizare Mycorrhizae are mutualistic associations of roots and fungi.

16) The high surface-to-volume ratio in leaves does not aid in ________.

Reduced water loss Does aid in CO2 absorption, more light absorption, and transpiration

8d) Which term describes an area where sugars are used or stored?

Sink A sink is an area where sugars are used or stored; typically, these are the roots and fruits of a plant. Which of the following

10d) The concentrations of some essential minerals are much higher in the vascular cylinder of roots than in the soil solution around the roots. What is the best explanation for this observation?

Some essential minerals are taken into the symplast by active transport Active transport into the symplast helps concentrate dissolved minerals that flow to the vascular cylinder, and the Casparian strip prevents back-flow out of the root down the concentration gradient.

12) A student is performing a chemical analysis of xylem sap. This student should not expect to find much _____.

Sugar Phloem, not xylem, transports sugar.

18b) The apoplast and symplast are two regions of the plant that serve as pathways for water and solute transport over both short and long distances. These pathways are represented by the arrows in the diagram below, which shows three adjacent cells in a leaf or root. Sort each statement into the appropriate bin.

The apoplastic pathway is a continuous route formed by cell walls, extracellular spaces, and the interior of dead xylem cells. The symplastic pathway is made up of the cytoplasm of cells. It is also continuous because plasmodesmata connect the cytoplasm of adjacent cells. These two pathways are separated by plasma membranes. Each pathway can transport water and solutes over both short and long distances.

8c) Which of the following statements about the distribution of sap throughout a plant is true?

The mechanism that explains the movement of sugars throughout a plant is called the pressure-flow hypothesis.

8e) Which of the following statements about xylem transport is true?

Water and minerals move through the root cortex into the xylem and upward through the stem and into leaves. Water and minerals that are taken up in the soil are transported from roots to leaves by the xylem.

11) Which of the following is a correct statement about a difference between xylem and phloem transport? -Active transport moves xylem sap but not phloem sap. -Phloem carries water and minerals; xylem carries organic molecules. -Transpiration moves phloem sap but not xylem sap. -Xylem sap moves up; phloem sap moves up or down. -Xylem sap moves from sugar source to sink, but phloem sap does not.

Xylem sap moves up; phloem sap moves up or down. The direction of movement in xylem is from roots to leaves. Phloem sap is transported throughout the plant from source to sink.

15) Which of the following primarily enters a plant somewhere other than through the roots? -water -potassium -nitrogen -carbon dioxide

carbon dioxide

2) Which of the following is an end product of photosynthesis?

glucose Carbon dioxide, water, and light energy are the inputs for photosynthesis. Glucose and oxygen are the end products.

Which of the following would tend to increase transpiration? Which of the following would tend to increase transpiration? -higher stomatal density -a rainstorm -spiny leaves -a thicker cuticle -sunken stomata

higher stomatal density

9e) _____ bonds are responsible for the cohesion of water molecules.

hydrogen Hydrogen bonds among water molecules are responsible for the tendency of those molecules to stick together.

1) The cohesiveness of water molecules is due to

hydrogen bonds between water molecules. Hydrogen bonding is the attraction of oppositely charged ends of polar molecules, such as water, to one another.

3) Plants must always compromise between _____ and _____.

maximizing photosynthesis ... minimizing water loss Structures, such as broad leaves, that enhance photosynthesis also maximize water loss. Plant form is generally a compromise between the two, depending on the plant's environment.

4) Mycorrhizae are _____.

mutualistic associations between plant roots and fungi Mycorrhizae greatly improve absorption of minerals and water from the soil.

21) Which of the following is an adaptation that enhances the uptake of water and minerals by roots?

mycorrhizae

5) Given that early land plants most likely share a common ancestor with green algae, the earliest land plants were most likely _____.

nonvascular plants that grew leafless, photosynthetic shoots

9a) The channels indicated by the pointer, are _____.

plasmodesmata Water and ions can pass from cell to cell via these channels. Also, recall that plasmodesmata are a type of cell junction.

What would enhance water uptake by a plant cell?

positive pressure on the surrounding solution

19) Which of the following is a net sugar source for a deciduous angiosperm tree?

roots in early spring

13) Which one of the following refers to the loss of water through the stomata in a plant's leaves?

transpiration The stomata in the leaves are entry points for the carbon dioxide necessary for photosynthesis, but they are also exit points for the evaporation of water by transpiration.

9d) _____ provide(s) the major force for the movement of water and solutes from roots to leaves.

transpiration Transpiration, the evaporation of water from leaves, exerts a pull that bears the primary responsibility for the movement of water and solutes from roots to leaves.

7) The physical property that predicts the direction of water flow is referred as ________.

water potential

A plant cell with a ψP of -0.65 MPa maintains a constant volume when bathed in a solution that has a ψP of -0.30 MPa and is in an open container. ψP of 0 MPa. ψP of -0.65 MPa. ψp of +0.65 MPa. ψP of +0.30 MPa. ψp of +0.35 MPa.

ψp of +0.35 MPa. -0.30 - (-)0.65 = 0.35