Chapter 25 - Cycling Carbon

Question 1

What did Keeling notice about CO2 levels?

Answer 1

• CO2 concentration reached its annual high point in spring then declined by 6 ppm to a minimum in early fall
• However, summertime removal of CO2 did not balance winter increase - up to now it has increased more than 25%

Question 2

What does 6 ppm mean in terms relative to CO2 levels?

Answer 2

Approximately 47 billion metric tons of CO2 were entering and leaving the atmosphere annually

Question 3

What exactly the carbon cycle?

Answer 3

The intricately linked network of biological and physical processes that shuttles carbon among rocks, soil, oceans, air, and organisms.

Question 4

What is the significance of the carbon cycle?

Answer 4

It provides a glimpse of the interactions that underpin ecology and promote biological diversity

Question 5

What processes introduce CO2 to the atmosphere?

Answer 5

1. geological inputs (volcanoes)
2. biological inputs (respiration)
3. human activities (burning of fossil fuels)

Question 6

What processes remove CO2 from the atmosphere?

Answer 6

1. geologic removal

2. biological removal (photosynthesis)

Question 7

What is the role and function of photosynthesis?

Answer 7

Photosynthesis convert energy from the sun into ATP, which they use to reduce CO2 to sugar. Carbon is then transferred to carbohydrates and oxygen is given off as a byproduct.

6CO2+6H20–>C6H1206+6O2

Question 8

What percent of annual CO2 does photosynthesis remove?

Answer 8

25%

Question 9

What is the role and function of respiration?

Answer 9

It uses oxygen to oxidize organic molecules to CO2, converting chemical energy in the organic compounds to ATP for use in cellular processes. Can be summarized by:
C6H1206+6O2–>6CO2+6H20

Question 10

Why does the Keeling curve demonstrate an upward increase in CO2?

Answer 10

Because of human burning of fossil fuels, which contributes a certain isotope of carbon

Question 11

How much CO2 was in the atmosphere 1000 years ago and how can we test for that?

Answer 11

When glacial ice forms in Antarctica and Greenland, it traps tiny bubbles of air, accumulating in layers.

Question 12

How can we tell that there is a causation between the industrial revolution and increased CO2 in the atmosphere?

Answer 12

Hans Suess measured relative abundances of 13C and 12C, which seemed to decrease, but 14C has increased, which indicates there is an increase due to fossil fuels.

Question 13

We find that half of CO2 released by human activities did not end up in air - where does it go?

Answer 13

It’s stored in oceans in the form of ions and salts.

Question 14

What is a primary producer and what are some examples?

Answer 14

Organisms that generate organic compounds that will provide food for other organisms in the local environment
Ex: plants, bacteria

Question 15

What is a consumer and what are some examples?

Answer 15

Organisms that obtain the carbon they need for growth and reproduction from the foods they eat, and they also gain energy by respiring food molecules
Ex: insects eating leaves, ducks eating algae

Question 16

What are decomposers and what are some examples?

Answer 16

Organisms that break down dead tissues

Ex: fungi, bacteria

Question 17

What is the food chain?

Answer 17

The linear transfer of carbon from one organism to another

Question 18

What is a food web?

Answer 18

An alternative to the food chain - showing the complexity of interactions and carbon consumers within the carbon cycle

Question 19

What are trophic pyramids/how are they used?

Answer 19

They are diagrams that show the amount of energy available at each level to feed the next-

Question 20

What is the pattern of trophic pyramids?

Answer 20

The higher the trophic level, the less available energy. This is because energy transfer is inefficient from level to level. Only 10-15% of levels are incorporated into biomass at the next level.

Question 21

Why is there such photosynthetic organism diversity?

Answer 21

Organisms all live in different habitats, and each is specialized to its unique habitat. This reflects structural and physiological adaptations.

Question 22

What can the carbon cycle tell us about evolution?

Answer 22

It changed the nature of Earth surface environments in ways that enabled new types of organisms to evolve

Question 23

How did the present carbon cycle come to be?

Answer 23

When photosynthesis and respiration are in balance, the oxygen generated by photosynthesis is completely consumed by respiration, but oxygen production can also exceed oxygen consumption. It can facilitate an increase in oxygen levels which is why our world is oxygen-rich