Lecture 9: Inside Leaves and Transpiration

Question 1

Densely packed, columnar-shaped, elongated cells full of chloroplasts

Answer 1

Palisade mesophyll

Question 2

Upper surface of a leaf

Answer 2

Upper epidermis with cuticle

Question 3

Xylem, phloem, bundle sheath along with nearby parenchyma

Answer 3

Vascular Bundle

Question 4

Loosely packed cells with large air spaces in between which allow movement and exchange of gases, specifically oxygen, carbon dioxide and water vapor.

Answer 4

Spongy mesophyll (also contain chloroplasts)

Question 5

Regulate the size of the stomata (holes in the leaf surface that allow gas exchange between the atmosphere and internal parts of the leaf)

Answer 5

Lower epidermis and guard cells

Question 6

Cellular organelles that contain types and colors of pigments other than chloroplasts

Answer 6

Chromoplasts

Question 7

Why do leaves change color in the fall?

Answer 7

mesophyll cell chloroplasts produce chlorophyll at a slower rate than earlier in the year. As the existing chlorophyll gets to the end of its functional lifespan and eventually degenerates the amount of chlorophyll over time declines. Chlorophyll replacement doesn’t make up for chlorophyll loss and so the green color fades out of the leaves. Meanwhile, the non-green pigments in the chromoplasts are holding their own or increasing in quantity, including the yellow and orange from the carotinoid pigments and the red from the anthocyanin pigments.

Question 8

Highly adapted for capturing light energy

Answer 8

palisade mesophyll

Question 9

Highly adapted for the transport of fluid

Answer 9

Vascular bundle

Question 10

The movement of water in the plant from root to stem to leaf and out through the stomata to the atmosphere

Answer 10

Transpiration (evapotranspiration)

Question 11

Rate of transpiration depend on

Answer 11

Light
Temperature
Humidity
Wind
Soil and water availability
Plant type

Question 12

Water pressure (turgor) in the root cells during the night or during cloudy days can push water and dissolved materials up into the stem. This root pressure is the cause of guttation which is the dew-like drops of water that are forced out of leaves.

Answer 12

Push Explanation

Question 13

The cohesion between water molecules due to the hydrogen bonds is very strong, and strong enough to hold the column of water together very tightly over long distances, like from root, through the stem and into the leaf. Although an individual bond is weak, there are so many that a column has enormous tensile strength.

Answer 13

Pull Explanation (cohesion-adhesion tension)

Question 14

Functions of transpiration

Answer 14

provides water for photosynthesis
cools plant
Moves minerals from root to leaf