REVIEW Chapters 31-33 Flashcards
Describe the three main types of plant tissues and their functions.
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
Describe the two main types of plant growth.
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)
Name the male and female types of plant growth.
Male: Stamen, made up of the anther and filament
Female: Carpel, made up of the stigma, style, ovary, and ovule
In which type of tissue does photosynthesis take place?
Ground tissue
What is “double fertilization”?
The union of 2 sperm cells with different nuclei of the embryo sac. One becomes an endosperm, while the other becomes a zygote.
What is the purpose of the fruit?
The fruit becomes a nutrition source for the seed/zygote.
Why are plants able to live so long?
Adult trees retain their meristems which allows for continued growth and repair. Thick wood also protects against disease.
What is a genetic benefit plants experience over their long life span?
A long life enhances fitness by increasing reproductive opportunities.
What are the main functions of the stomata?
Allowing gases such as CO2, O2, and water vapor to move rapidly into and out of the leaf
How is the rate of transpiration affected by drought?
Decreases, due to the closing of the stomata
How is the rate is transpiration affected by wind?
Increases, because wind blows moisture off the leaf which created a drier atmosphere in which a gradient from leaf to air is created.
How is the rate of transpiration affected by sunlight?
The rate of transpiration is increased, because light stimulated the opening of the stomata.
How is rate of transpiration affected by high humidity?
The rate of transpiration is decreased due to the atmosphere containing more moisture.
Name and describe the two routes that water and minerals can take to get from the soil into the xylem.
1) Extracellular route, via cell walls an spaces between cells; stopped by the Casparian strip
2) Intracellular route, via cell interiors through plasmodesmata
Describe the cohesion-tension mechanism thawed the movement of xylem sap.
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.
What creates “root pressure”?
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.
What stimulate guard cells to open?
Guard cells open by the presence of light, the loss of carbon dioxide and normal circadian rhythms.
Describe the process by which stomata open and close.
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.
Describe the pressure-flow mechanism that drives the movement of phloem sap.
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.
What is the symplast?
The transport route that connects all the parts of a plant so informational molecules such as RNA and proteins can move freely between cells.
List the six main elements essential to plants.
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphate, and Sulfur
Describe how plants use the process of cation exchange to absorb nutrients from the soil.
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.
Describe the types of symbiotic relationships that plants might have that allow them to receive sufficient nitrogen from the soil.
- 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.
List the name and major functions of the five major plant hormones.
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)
