Biology chapter 9

What is the function of the palisade mesophyll?

*Palisade mesophyll: They are cells near the top of the leaf that are the most responsible for light absorption and photosynthesis. It contains lots of chloroplasts on the top side of the leaf.

What is the function of the spongy mesophyll?

*Spongy mesophyll: It is a layer of sparsely spaced cells where there are channels for gas exchange. The air pockets allow for efficient gas exchange.

What is the function of the stomata and the guard cells?

*Stomata and guard cells: Stomata are holes that let water out and carbon dioxide in, it's opening and closing is regulated by the guard cells. They are at the bottom of the leaves where it is cooler, so there is less water loss.

The Basic leaf Structure. What is the function of the cuticle?

*The cuticle: This protects the plant against water loss and insects; and if no cuticle is present, the epidermis protects the leaf.

What is the function of epidermis?

*The epidermis: It is a protective layer and if no cuticle exist, then it plays the role. They are flat and tightly packed on both sides of the leaf.

What is the function of the vein of the leaf?

*Vein:only vascular plants have veins. The vein is a vascular bundle of xylem and phloem that carry water and products of photosynthesis. They are in the middle of the leaf so they can service all leaf cells.

Plant Water and Mineral Movement. . What is transpiration?

Transpiration is the process where water travels from the root of a plant to the leaves where it exits through the stomata as water vapor. Most or 90% of water taken in by the roots is lost as transpiration

Roots and fluid movement in plants. What is the function of the roots?

-The main function of roots is to absorb minerals and water from the soil; this is possible due to its many branches and root hairs.

Roots and fluid movements in plants. Water moves from the soil into the root because:

-There is tension from the water column moving water from the roots through the xylem. -There is a higher solute concentration in the roots than the soil.

Water movement. How does water loss via transpiration occur?

-Water lost via transpiration leaves through the leaves. But, that evaporation actually pulls up the column of water all the way from the roots. Roots absorb the water that will eventually be lost via transpiration.

Stomata and guard cells. 1. Where guard cells found? 2.What is the function of guard cells?

1*Around the stomata (openings in the leaves) are guard cells. 2*Guard cells control the opening and closing of the stomata.

The vessel elements. 1,What are plant cells made from? 2,What is the additional cell wall ?

1*Plants cells have cell walls made of cellulose. 2*The vessel elements have an additional cell wall made of another complex carbohydrate called lignin.

How the turgor pressure works. 1.What causes the stomata to open?

1*When the guard cells swell with water, they cause the stomata to open.

The cohesion-tension theory of plant fluid movement. What causes water to exit the stomata ?

1-Water exits the stomata of a leaf and evaporates. This is due to the fact that there is a higher concentration of water within the leaf than in the atmosphere.

2.What causes stomata to close?

2*When the guard cells shrink because of lack of water, they cause the stomata to close.

How is water replaced after transpiration?

2-Water lost by transpiration is replaced by water from the vessels. Due to the cohesion between water molecules leaving through the stomata (by pulling a column of water up).

3. What is the stomata essential for?

3*The stomata let water out but they also let essential carbon dioxide in so when they are closed that be temporary or else the plant won't have the carbon dioxide it needs for photosynthesis.

3. What is the function of lignified cell walls? 4. What is its extra function?

3*These lignified cell walls are strong and waterproof, which is especially helpful when water has to move long distances, like up the trunk of a tree. 4*The extra lay of lignin is also good for support of tall plants, like trees

3.Why does excess water transpire?

3*This makes sense ... when the plant has plenty of water, it can afford to open the stomata and let excess water transpire.

3.What happens to the water column in the vessel?

3-The water column in the vessel is maintained by cohesion(keeping it together) and adhesion(attraction to the sides of the vessel , pulling against force of gravity).

4.How does the turgor pressure affect the stomata? 5.What is turgor pressure?

4*The stomata are said to open and close due to the turgor pressure of the guard cells. 5*Turgor pressure is the pressure that the liquid part of the cell exerts on the cell wall.

4.What happens when the plant has no water?

4*When the plant does not have enough water, the guard cells cause the stomata to close to conserve water.

4.How does tension affects the water in the columns of the xylem? 5. How does water move through the roots? 6. How does the pulling occur?

4-Tension occurs in the columns of water in the xylem, due to transpiration, then cohesion and adhesion. 5-Water is pulled from the root cortex into the xylem cells. 6-The pulling sucks the water from the soil into the root. by a transpiration pull

5.What determines the movement of water?

5*The movement of water, in and out of the guard cells is largely determined by the potassium ion movement.

6.What is the deal with potassium in the cell?

6*When there is light ATP-powered membrane protein pumps actively pump potassium into the cell. The higher potassium concentration causes water to enter the cell via osmosis.

7.What happens to the guard cells during times of drought?

7*During times of drought, a hormone is being produced to cause potassium to leave the guard cells.

What are the effects of transpiration on the plant?

The effects of transpiration on the plant: 1. Carries water to various parts of the plant, which is needed for photosynthesis. 2. Carries minerals along with the water. 3. Cools down the plant when water evaporates from the stomata (just like a person sweating).

The vein structure. What are the two structures the vein of a plant contains?

The vein of a plant actually contains two structures 1.Xylem: It carries water and dissolved minerals up through the plant. 2.Phloem: Carries sugars and other products from the place where they are produced to the place where they are stored.

The xylem. (Drawing and labelling in book) What is the xylem made of, and what are its function?

The xylem is made of two types of dead cells. Which are: -Tracheid: have tapered ends that fit together and water moves between them. -Vessel elements: have thick walls with pores in them that allow water movement in one continuous column.