Chapter 6: Plant Adaptations to the Environment

Question 1

Any plant that produces as its first step in photosynthesis the 3-carbon compound phosphoglyceric acid

Answer 1

C3 plant

Question 2

A plant that has evolved a modified form of photosynthesis that increases water-use efficiency in warmer and drier environments

Answer 2

C4 plant and CAM plant

Question 3

C4 photosynthetic pathway

Answer 3

Involves 2 distinct types of photosynthetic cells: the mesophyll cells and the bundle sheath cells

CO2 initially reacts with PEP to form 4-carbon compounds in the mesophyll cells

These compounds are then transported into the bundle sheath cells where they are converted into CO2 and undergo the C3 photosynthetic pathway (Calvin cycle)

Question 4

CAM pathway (crassulacean acid metabolism)

Answer 4

Photosynthetic pathway (using same processes involved in C4 pathway) that separates the processes of carbon dioxide uptake and fixation when growing under arid conditions

It takes up gaseous carbon dioxide at night, when stomata are open, and converts it into simple sugars during the day, when stomata are closed

Question 5

Difference between the rate of carbon uptake in photosynthesis and carbon loss in respiration

Answer 5

net photosynthesis

Question 6

Depth of water or level of light at which photosynthesis and respiration balance each other

Answer 6

light compensation point

Question 7

Able to grow and reproduce under low light conditions

Answer 7

shade-tolerant

Question 8

Amount of light at which plants achieve the maximum rate of photosynthesis

Answer 8

light saturation point

Question 9

The slowing or stopping of a plant process by light

Answer 9

photoinhibition

Question 10

Loss of water vapor from a plant to the outside atmosphere

Answer 10

transpiration

Question 11

Pores in the leaf or stem of a plant that allow gaseous exchange between the internal tissues and the atmosphere

Answer 11

stomata

Question 12

Growing and reproducing best under high light conditions

Growing poorly and failing to reproduce under low light conditions

Answer 12

shade-intolerant

Question 13

Dry, especially in soil

Answer 13

xeric

Question 14

Moderately moist

Answer 14

mesic

Question 15

A layer of still air close to or at the surface of an object

Answer 15

boundary layer

Question 16

Essential nutrient needed in very small quantities by plants and animals

Answer 16

micronutrient

Question 17

Essential nutrients plants and animals need in large amounts

Answer 17

macronutrient

Question 18

An erect respiratory root that protrudes above waterlogged soils

Typical of bald cypress and mangroves

Answer 18

pneumatophore

Question 19

Let’s talk about trade-off between growth rate and tolerance

Answer 19

“Plant adaptations to the abiotic environment represent a fundamental trade-off between phenotypic characteristics that enable high rates of photosynthesis and plant growth in high resource/energy environments and the ability to tolerate (survive, grow, and reproduce) under low resource/energy conditions.”

“The set of phenotypic characteristics that enhance a species’ carbon gain (photosynthesis and plant growth) under high resource/energy environments limit its tolerance (survival and growth) of low resource/energy conditions.”

“Conversely, the phenotypic characteristics that enable a species to survive, grow, and reproduce under low resource/energy conditions limit its ability to maximize growth rate in high resource/energy environments.”

Question 20

Plants exhibit what 2 primary responses to CO2?

Answer 20

Increase in photosynthesis

Reduction in stomatal conductance

Question 21

Let’s talk about plant response to increasing atmospheric carbon dioxide

Answer 21

Plants exhibit 2 primary responses to CO2:

1. Increase in photosynthesis
2. Reduction in stomatal conductance

The increase in photosynthesis occurs primarily in C3 plant species and is a response to reduced photorespiration.

The decrease in stomatal conductance functions to increase water-use efficiency.

Increased rates of photosynthesis result in an increase in growth rates.