4.2 Energy Flow

Question 1

What are different forms of energy in an ecosystem?

Answer 1

• Sunlight
  
  • Chemical Energy
  • Heat Energy

Question 2

Why is energy transfer so inefficient?

Answer 2

Energy is lost at each trophic level
Growth and Reproduction (Energy available for consumers)

• Cellular Respiration (Heat Energy due to movement and homeostasis)
• Not consumed (not everything is consumed or used)
• Not assimilated (Excretion/Egestion/Waste elimination due to non-absorption/organism might die before being consumed) → provide energy for detritus

Question 3

Suggest reasons for the few number of tertiary consumers or higher in ecosystems.

Answer 3

• Hawks, as a tertiary consumer only get a very small amount of energy from the ecosystem because so much is lost on each trophic level therefore, it takes much more prey to keep the Hawk surviving (insufficient energy to support)
  
  • More Hawks means more competition which is difficult to maintain due to the already small number of prey

Question 4

What groups of autotrophs carry out photosynthesis?

Answer 4

• Plants
• eukaryotic algae
• cyanobacteria
  These are producers

Question 5

How do heterotrophs gain energy?

Answer 5

They are indirectly dependent on it as they use carbon compounds in their food as a source of energy.
Chemical energy in carbon compounds flows through food chains by means of feeding.
Carbon compounds derive by photosynthesis in producers.

Question 6

How are carbon compounds formed?

Answer 6

Light energy is converted to chemical energy in carbon compounds by photosynthesis (producers)

When producers absorb sunlight they convert light energy into chemical energy stored in carbohydrates, lipids and other carbon compounds

Question 7

How do organisms lose energy at each trophic level?

Answer 7

Cellular Respiration - heat energy is lost due to homeostasis
Not consumed - not everything is consumed or used
Not assimilated - (Excretion/Egestion/Waste elimination due to non-absorption/organism might die before being consumed) → provide energy for detritus

Question 8

What do living organisms need energy for?

Answer 8

Energy released by respiration is used in living organisms and converted to heat.
Cell activities:
-synthesizing large molecules like DNA, RNA and proteins
-pumping molecules across membranes by active transport
-moving things around inside the cell (mitosis/meiosis, vesicles or protein fibres for muscle contraction)

Question 9

What is ATP?

Answer 9

ATP supplies energy for cellular activities. (a cell produces its own supply through cell respiration)

Question 10

What energy conversions can living organisms perform?

Answer 10

• Light energy to chemical energy (photosynthesis)
  -Chemical energy to kinetic energy (muscle contraction)
  -Chemical energy to electrical energy (nerve cells)
  -Chemical energy to heat energy (adipose tissue)
  Living organisms cannot convert heat to other forms of energy

Question 11

What do auto- and heterotrophs obtain from their abiotic environment?

Answer 11

Living organisms need a supply of chemical elements known as inorganic material which autotrophs can convert using light energy into chemical energy. This is makes it possible for heterotrophs to gain carbon compounds in their food.

Question 12

Since nutrients are finite and in limited supply in an ecosystem how are they maintained?

Answer 12

The supply of inorganic nutrients is maintained by nutrient cycling.
Chemical elements can be endlessly recycled (is not lost like heat energy) as after usage they are returned to the environment.

Question 13

What are the three requirements for sustainability in ecosystems?

Answer 13

Ecosystems have the potential to be sustainable over long periods of time, depending on:

• nutrient availability
• detoxification of waste products
• energy availability

Question 14

Describe the movement of energy and nutrients in an ecosystem.

Answer 14

ecosystem is a community and its abiotic environment;
solar energy collected by autotrophs/plants (via photosynthesis);
moves through trophic levels via food;
only 5 to 20% transferred from one trophic level to next / never
100% efficient;
lost as metabolic heat/organic waste;
energy flow can be illustrated by pyramid shape;
organisms absorb nutrients from food/environment;
nutrients occur as complex organic matter in living organisms;
after death, saprotrophic bacteria and fungi (decomposers) breakdown
complex organic matter;
breakdown products are simpler substances;
absorbed into plants for resynthesis into complex organic matter/recycled;