REVIEW Chapters 31-33

Question 0

Describe the three main types of plant tissues and their functions.

Answer 0

1) Dermal tissue - Plant’s outer protective covering. Forms a line of defense against physical damage and infectious organisms.
2) Vascular tissue - Provides support and long distance transport between the root and shoot system.
3) Ground tissue - Accounts for most of the bulk of a young plant filling spaces between the epidermis and vascular tissue. Diverse functions include photosynthesis, storage and support

Question 1

Describe the two main types of plant growth.

Answer 1

1) Primary growth - Cell division within the apical meristem lengthens roots and shoots (plant grows taller)
2) Secondary growth - Cell division in lateral meristems thickens roots and stems (plant grows wider)

Question 2

Name the male and female types of plant growth.

Answer 2

Male: Stamen, made up of the anther and filament
Female: Carpel, made up of the stigma, style, ovary, and ovule

Question 3

In which type of tissue does photosynthesis take place?

Answer 3

Ground tissue

Question 4

What is “double fertilization”?

Answer 4

The union of 2 sperm cells with different nuclei of the embryo sac. One becomes an endosperm, while the other becomes a zygote.

Question 5

What is the purpose of the fruit?

Answer 5

The fruit becomes a nutrition source for the seed/zygote.

Question 6

Why are plants able to live so long?

Answer 6

Adult trees retain their meristems which allows for continued growth and repair. Thick wood also protects against disease.

Question 7

What is a genetic benefit plants experience over their long life span?

Answer 7

A long life enhances fitness by increasing reproductive opportunities.

Question 8

What are the main functions of the stomata?

Answer 8

Allowing gases such as CO2, O2, and water vapor to move rapidly into and out of the leaf

Question 9

How is the rate of transpiration affected by drought?

Answer 9

Decreases, due to the closing of the stomata

Question 10

How is the rate is transpiration affected by wind?

Answer 10

Increases, because wind blows moisture off the leaf which created a drier atmosphere in which a gradient from leaf to air is created.

Question 11

How is the rate of transpiration affected by sunlight?

Answer 11

The rate of transpiration is increased, because light stimulated the opening of the stomata.

Question 13

How is rate of transpiration affected by high humidity?

Answer 13

The rate of transpiration is decreased due to the atmosphere containing more moisture.

Question 14

Name and describe the two routes that water and minerals can take to get from the soil into the xylem.

Answer 14

1) Extracellular route, via cell walls an spaces between cells; stopped by the Casparian strip
2) Intracellular route, via cell interiors through plasmodesmata

Question 14

Describe the cohesion-tension mechanism thawed the movement of xylem sap.

Answer 14

Cohesion occurs between water molecules as well as adhesion between water molecules and the cell wall. This created continuous strings of water pulled up by transpiration. The adhesion between water and the cell wall counteracts the downward pull of gravity, therefore assisting the upward movement of the xylem sap.

Question 15

What creates “root pressure”?

Answer 15

Root cells actively pump inorganic ions into the xylem and the root’s endodermis holds the ions there. As the ions accumulate, water ends to enter by osmosis.

Question 16

What stimulate guard cells to open?

Answer 16

Guard cells open by the presence of light, the loss of carbon dioxide and normal circadian rhythms.

Question 17

Describe the process by which stomata open and close.

Answer 17

Open:

1) Potassium is actively taken up by guard cells from nearby cells.
2) This created an osmotic gradient ad water follows.
3) Uneven cell walls of guard cells cause them to bow whether is taken up.
4) Guard cell bowing causes the pore of the stoma to open.

Close:

1) Guard cells lose K+ ions.
2) Guard cells become flaccid.
3) Stoma closes.

Question 19

Describe the pressure-flow mechanism that drives the movement of phloem sap.

Answer 19

At the sugar source, sugar is loaded from a photosynthetic cell to the phloem tube by active transport. This raises the sugar concentration inside the phloem tube. This high concentration attracts water into the tube; the inward flow of water raises the water pressure at the source end of the phloem tube. At the sugar sink, sugar and water leave the phloem. Sugar concentration is lowered at the sink end and water follows into the xylem by osmosis. The building of water pressure at the source and its reduction at the sink causes phloem sap to flow from source to sink – down a gradient of water pressure.

Question 20

What is the symplast?

Answer 20

The transport route that connects all the parts of a plant so informational molecules such as RNA and proteins can move freely between cells.

Question 21

List the six main elements essential to plants.

Answer 21

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphate, and Sulfur

Question 22

Describe how plants use the process of cation exchange to absorb nutrients from the soil.

Answer 22

Cation exchange is the process by which H+ is exchanged for other cations (Ca+2, Mg+2, K+, Fe+2) that are attached to the soil.

Question 23

Describe the types of symbiotic relationships that plants might have that allow them to receive sufficient nitrogen from the soil.

Answer 23

• Nitrogen-fixing bacteria in the soil converts N2 gas from the air into forms usable by plants. Legumes form root nodules to house bacteria.
• Mycorrhizae is fungus. This increases the area for absorption of water and minerals, selectively absorbs phosphate and other minerals, releases growth factors and antibiotics into the soil. This has evolved with plants.

BENEFIT: Mycorrhizae and nitrogen-fixing bacteria benefit by receiving sugars from the plants they colonize.

Question 24

List the name and major functions of the five major plant hormones.

Answer 24

1) Auxins – Promotes primary plant growth, increases the rate of cell elongation in response to directional stimuli, and promotes apical dominance
2) Cytokinins – Promotes cell division, ensures that roots and shoots are growing at equal rates, stimulates the growth of fruit and activates lateral branching (secondary growth)
3) Gibberellins – Necessary for seed germination, stimulates production of amylase and the production of ATP in the presence of water, used for cellulose synthesis for cell wall formation and causes stem elongation “bolting” by promoting cell elongation and cell division
4) Abscisic Acid – Inhibits plant growth and development, promotes the death of leaves, is responsible for seed dormancy, and prevents excess water loss by causing the closure of the stomata
5) Ethylene – Stimulates maturation and aging (ripening fruit, leaf loss, flower deaths)

Question 25

What do auxins do?

Answer 25

Promotes primary plant growth, increases the rate of cell elongation in response to directional stimuli, and promotes apical dominance

Question 26

What do cytokinins do?

Answer 26

Promotes cell division, ensures that roots and shoots are growing at equal rates, stimulates the growth of fruit and activates lateral branching (secondary growth)

Question 27

What do gibberellins do?

Answer 27

Necessary for seed germination, stimulates production of amylase and the production of ATP in the presence of water, used for cellulose synthesis for cell wall formation and causes stem elongation “bolting” by promoting cell elongation and cell division

Question 28

What does abscisic acid do?

Answer 28

Inhibits plant growth and development, promotes the death of leaves, is responsible for seed dormancy, and prevents excess water loss by causing the closure of the stomata

Question 29

What does ethylene do?

Answer 29

Stimulates maturation and aging (ripening fruit, leaf loss, flower deaths)

Question 30

List three tropisms.

Answer 30

1) Phototropism
2) Gravitropism
3) Thigmotropism

Question 31

What determines if a plant is a “short-day” or “long-day” plant?

Answer 31

The circumstances necessary for a plant to flower. “Short-day” plants, such as chrysanthemums or poinsettias, generally flower in the late summer, fall, or winter when light periods shorten. “Long-day” plants, such as spinach, lettuce, and cereal grains, generally flower in late spring or early summer when light periods lengthen.

Question 32

How do plants use physical and chemical responses to protect themselves from harm?

Answer 32

Physical: Thorns
Chemical: Distasteful or toxic compounds

Levels of Defense:

1) The first line of defense against infection is the physical barrier of the plant’s epidermis. If this fails, plant cells damaged by infection seal off the infected areas and release microbe-killing chemicals that signal nearly cells to mount a similar chemical defense.
2) Hormones trigger generalized defense responses in other organs in the process of systematic acquired resistance.