Primary Productions

Question 1

The process by which autotrophic organisms (mainly plants) take in CO₂ from the atmosphere through photosynthesis to produce organic matter.

Answer 1

primary production

Question 2

Why is primary production important?

Answer 2

It is the base of the food chain, driving energy and carbon flow in ecosystems.

Question 3

What percentage of Earth’s surface is vegetated?

Answer 3

71% of the terrestrial environment is covered by vegetation.

Question 4

The total amount of CO₂ converted into sugars by photosynthesis.

Answer 4

Gross Primary Production (GPP)

Question 5

The CO₂ lost as plants break down sugars to generate energy for growth and maintenance.

Answer 5

Plant Respiration (RP)

Question 6

The amount of energy available for plant growth and herbivores.

Answer 6

Net Primary Production (NPP)

Question 7

NPP = GPP – RP

Answer 7

Net Primary Production (NPP)

Question 8

The total organic carbon accumulation in an ecosystem.

Answer 8

Net Ecosystem Production (NEP)

Question 9

Formula: NEP = NPP – (Rh + FD + FL)

Answer 9

Net Ecosystem Production (NEP)

Question 10

Respiration by decomposers.

Answer 10

Rh

Question 11

Carbon loss from fires, harvesting.

Answer 11

FD

Question 12

Carbon loss through leaching.

Answer 12

FL

Question 13

Why is carbon used as a currency for measuring GPP?

Answer 13

CO₂ changes in the atmosphere are easier to track than direct energy accumulation.

Question 14

How do scientists measure GPP at the leaf level?

Answer 14

By tracking CO₂ exchange

Question 15

Respiration (RP) is measured.

Answer 15

In darkness

Question 16

GPP is determined by subtracting RP.

Answer 16

In light

Question 17

The balance of CO₂ in and out of an ecosystem, measured using eddy covariance.

Answer 17

Net Ecosystem Exchange (NEE)

Question 18

Formula: NEE = CO₂ out – CO₂ in

Answer 18

Net Ecosystem Exchange (NEE)

Question 19

If NEE is more negative

Answer 19

More carbon is stored.

Question 20

If NEE is more positive

Answer 20

More CO₂ is released.

Question 21

What is the main pigment responsible for photosynthesis?

Answer 21

Chlorophyll

Question 22

absorbs light in red and blue wavelengths.

Answer 22

Chlorophyll

Question 23

The light level where photosynthesis = respiration, meaning no net carbon gain.

Answer 23

compensation point in photosynthesis

Question 24

How does temperature affect photosynthesis?

Answer 24

Photosynthesis follows a unimodal response

Question 25

Increases with temperature up to an ______

Answer 25

optimum

Question 26

Declines at high temperatures due to ______

Answer 26

enzyme breakdown

Question 27

Why do plants close their stomata in dry conditions?

Answer 27

To reduce water loss, but this also limits CO₂ uptake, reducing photosynthesis.

Question 28

A wasteful process where Rubisco binds to O₂ instead of CO₂, reducing photosynthesis efficiency.

Answer 28

photorespiration

Question 29

How do C3 plants fix carbon?

Answer 29

They use Rubisco to fix CO₂ directly in the Calvin Cycle.

Question 30

Why are C3 plants inefficient in hot, dry conditions?

Answer 30

Photorespiration reduces CO₂ fixation, wasting energy.

Question 31

Examples of C3 plants?

Answer 31

Wheat, rice, trees, most plants.

Question 32

How do C4 plants avoid photorespiration?

Answer 32

They separate CO₂ fixation into two cell types

Question 33

_______ Cells fix CO₂ using PEP carboxylase, forming a 4-carbon compound.

Answer 33

Mesophyll

Question 34

__________ cells release CO₂ for the Calvin Cycle, preventing O₂ interference.

Answer 34

Bundle sheath

Question 35

Why are C4 plants more efficient in warm environments?

Answer 35

They use water more efficiently and have higher photosynthesis rates under high light and temperature.

Question 36

Examples of C4 plants?

Answer 36

Corn, sugarcane, grasses.

Question 37

How do CAM plants conserve water?

Answer 37

Stomata open at night to take in CO₂. CO₂ is stored as an organic acid and used during the day when the stomata are closed.

Question 38

Why do CAM plants grow slowly?

Answer 38

They limit water loss but also have low productivity.

Question 39

Examples of CAM plants?

Answer 39

Cacti, succulents, pineapples.

Question 40

What determines vegetation type in a biome?

Answer 40

Temperature, water availability, and disturbance (fire, grazing).

Question 41

Characteristics: Cold, low vegetation, permafrost Ex: Mosses, shrubs (C3)

Answer 41

Tundra

Question 42

Characteristics: Evergreen conifers, acidic soil Ex: Spruce, pine (C3)

Answer 42

Taiga (Boreal Forest)

Question 43

Characteristics: Deciduous trees, moderate rain Ex: Oak, maple (C3)

Answer 43

Temperate Forest

Question 44

Characteristics: Deep-rooted grasses, seasonal rain Ex: Tallgrass (C3-C4)

Answer 44

Grasslands

Question 45

Characteristics: Low water, slow growth Ex: Cacti (CAM), shrubs (C4)

Answer 45

Deserts

Question 46

Characteristics: Grass-dominated, scattered trees Ex: Acacia, grasses (C4)

Answer 46

Savanna

Question 47

The total leaf area per unit ground area – determines light absorption and photosynthesis.

Answer 47

Leaf Area Index (LAI)

Question 48

Which biome contributes the most to global NPP

Answer 48

Tropical rainforests (60% of global NPP)

Question 49

Why are forests twice as productive as grasslands per unit area?

Answer 49

They have higher LAI, meaning more light absorption and longer growing seasons.