Energy Transfer And Nutrient Cycles

Question 1

What does abiotic mean?

Answer 1

Non living

Question 2

Give to uses of the sugars produced in plants during photosynthesis

Answer 2

1. Used in respiration for growth

2. To make cellulose

Question 3

What is biomass?

Answer 3

Biomass is the chemical energy stored in the plant

Question 4

What is dry mass?

Answer 4

Dry mass is the mass of the organism with the water removed

Question 5

How do you measure dry mass?

Answer 5

1. Organism is dried, often in an oven at a low temperature
2. Weigh organism at regular intervals (e.g. Once a day at 2pm)
3. When mass becomes constant, organism is dried
4. Mass of carbon present is 50% of dry mass

Question 6

How can calorimetry be used to estimate the amount of chemical energy stored in biomass

Answer 6

Burn biomass in a calorimeter. The amount of heat given off tells you how much energy is in it. A sample of dry biomass is burnt and the energy released is used to heat a known volume of water. The change in temperature of the water is used to calculate the chemical energy of the dry biomass

Question 7

What is gross primary production?

Answer 7

The total amount of chemical energy converted from light energy by plants, in a given area, in a given time

Question 8

What is respiratory loss?

Answer 8

The amount of energy lost to the environment as heat when plants respire

Question 9

What is net primary production?

Answer 9

The energy left in the organism after respiratory loss

Question 10

What is the primary production formula?

Answer 10

NPP = GPP - R

Question 11

How to calculate net production

Answer 11

N = I - (F + R)

N = net production
I = chemical energy in ingested food
F = chemical energy lost in faeces and urine
R = energy lost through respiration

Question 12

Efficiency of energy transfer equation

Answer 12

% efficiency of energy transfer = (net production of trophic level/net production of previous trophic level) x 100

Question 13

How to increase efficiency of food webs

Answer 13

The energy lost to other organisms can be reduced through the simplification of food webs

The energy lost through the respiration of livestock can be reduced

Question 14

How do farmers remove pests?

Answer 14

Chemical pesticides

Biological agents

Question 15

How do farmers reduce respiratory loss in live stock?

Answer 15

Kept in pens to restrict movement

Pens inside so it’s warm so no energy is wasted by generating body heat

Question 16

What do Saprobionts do?

Answer 16

They feed on the remains of dead plants and animals and on their waste products, breaking them down.

Saprobionts secrete enzymes and digest their food externally then absorb the nutrients they need. During this process, organic molecules are broken down into inorganic ions.

Question 17

What is extracellular digestion?

Answer 17

When a decomposer secretes enzymes and digest their food externally and then absorb the nutrients they need

Question 18

What is mycorrihizae?

Answer 18

The symbiotic relationship formed between fungi and plant roots

Question 19

How do fungi attach to plant roots

Answer 19

Fungi are made up of long thin strands called hyphae. The hyphae connect to the plants roots

Question 20

How does mycorrhizae benefit each organism?

Answer 20

The hyphae in the fungi greatly increase the surface area of the plants root system, helping the plant to absorb ions from the soil that are usually scarce. Hyphae also increase the uptake of water by the plant.

Fungi obtain organic compounds, such as glucose, from the plant

Question 21

What are the steps involved in the nitrogen cycle?

Answer 21

Nitrogen fixation
Ammonification
Nitrification
Denitrification

Question 22

What is nitrogen fixation?

Answer 22

Nitrogen fixation is when nitrogen gas in the atmosphere is turned into nitrogen containing compounds.

Question 23

How is biological nitrogen fixation carried out?

Answer 23

Biological nitrogen fixation is carried out by bacteria such as Rhizobium. It turns nitrogen into ammonia. The ammonia can then be used by plant

Question 24

Explain the mutualistic relationship between rhizobium and plants

Answer 24

Rhizobium are found inside root modules of leguminous plants. They provide the plant with nitrogen compounds and the plant provides them with carbohydrates

Question 25

What is ammonification?

Answer 25

Ammonification is when nitrogen compounds from dead organisms are turned into ammonia and ammonium ions by Saprobionts. Animal waste also contains nitrogen compounds. These are also turned into ammonia and ammonium ions by Saprobionts

Question 26

What is nitrification?

Answer 26

Nitrification is when ammonia and ammonium ions in the soul are changed into nitrogen compounds that can then be used by plants. First nitrifying bacteria called Nitrosomonas change ammonia and ammonium ions into nitrates. Then other nitrifying bacteria called Nitrobacter change nitrites into nitrates

Question 27

What is denitrification?

Answer 27

Denitrification is when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria via anaerobic respiration

Question 28

Phosphorus Cycle

Answer 28

Phosphate ions in rocks are released into the soul by weathering
Phosphate ions are taking into plants through roots
Phosphate ions are passed through food chain as animals each plants and one another
Phosphate ions are lost from the animals in waste products
When plants and animals die, Saprobionts break them down, as well as their waste products, said the releasing phosphate ions into the soil for assimilation by plants
Weathering of rocks release phosphate ions into sea, lakes and rivers
Aquatic producers take up phosphate ions
Phosphate ions passed on to sea birds after consuming fish
Sea birds produce guano waste that releases phosphate ions into the soil