2.2 - Communities And Ecosystems

Question 1

What is a community

Answer 1

A community is a group of populations living and interacting with each other in a common habitat

Question 2

Is an ecosystem a community

Answer 2

An ecosystem is a community and the physical environment it interacts a with

Question 3

Give an example of how a community interacts with its physical enviroment to create a unique ecosystem

Answer 3

An example of an ecological community is a coral reef ecosystem. The coral reef ecosystem consists of various populations of living organisms such as coral polyps, fish, crustaceans, mollusks, algae, and other marine creatures that interact with each other and their non-living environment.

These organisms form a complex community that is adapted to the specific conditions of the coral reef ecosystem, including the temperature, light, water chemistry, and physical structure of the reef. Coral reefs require specific abiotic factors such as warm water temperatures, clear and shallow water, and high levels of sunlight to survive.

The interactions among the different species in the community help to maintain the health and stability of the ecosystem. For example, the corals provide a habitat for fish and other organisms, while the fish help to keep the reef healthy and clean by grazing on algae that grows on the corals and by removing dead or decaying matter. In these ways, the coral reef community and its physical environment are intricately connected and interact with each other to create a diverse and productive ecosystem.

Question 4

What is photosynthesis

Answer 4

Primary producers in the majority of ecosystems convert light energy into chemical energy in the process of photosynthesis

The photosynthesis reaction is:
Carbon dioxide + water —> glucose + oxygen

Question 5

What are the inputs of photosynthesis

Answer 5

sunlight as energy source, carbon dioxide, and water

Question 6

What are the processes of photosynthesis

Answer 6

inside chloroplasts, chlorophyll captures certain visible wavelengths of sunlight energy and stores this as chemical energy

Question 7

What are the outputs of photosynthesis

Answer 7

Glucose and oxygen

Question 8

What are the transformations of photosynthesis

Answer 8

light energy is transformed into stored chemical energy (in organic matter e.g. carbohydrates, fats and proteins)

Question 9

What does the process of photosynthesis convert

Answer 9

Photosynthesis produces the raw material for producing biomass
The glucose produced during photosynthesis is used as an energy source for the plant but also as the basic starting material for other organic molecules (e.g. cellulose and starch)

Question 10

What does photosynthesis transfer light energy into

Answer 10

Chemical energy in biological molecules

Question 11

What are most of the sugars synthesised by plants used for

Answer 11

Most of these sugars synthesised by plants are used by the plant as respiratory substrates
- A respiratory substrate is a molecule (such as glucose) that can be used in respiration, to release energy for growth

Question 12

What are the minority of sugars used for in photosynthesis

Answer 12

1. Starch - a complex carbohydrate molecule (formed from many glucose molecules) that acts as a short-term energy storage molecule
2. Cellulose - another complex carbohydrate molecule (also formed from many glucose molecules) that acts as a structural component of plant cell walls
3. Lipids - plant cells can convert the sugars produced during photosynthesis into lipids, which act as another type of (longer-term) energy storage molecule
4. Proteins - plant cells can also combine the sugars produced during photosynthesis with nitrates to make amino acids, which can then be used to produce proteins

Question 13

What is biomass

Answer 13

The biomass is the mass of living material. It can also be thought of as the chemical energy that is stored within the plant

Question 14

What is respiration

Answer 14

Respiration and photosynthesis can be described as processes with inputs, outputs, and transformations of energy and matter
Respiration is the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy

Question 15

What is aerobic respiration

Answer 15

A chemical reaction which converts glucose into cellular energy in the presence of oxygen

Question 16

What is the formula for aerobic respiration

Answer 16

Glucose + oxygen —> carbon dioxide + water

Question 17

What are the inputs of aerobic respiration

Answer 17

Organic matter and oxygen

Question 18

What are the processes in aerobic respiration

Answer 18

Oxidation processes inside cells

Question 19

What are the outputs of aerobic respiration

Answer 19

Release of energy for work and heat

Question 20

What are the transformation of aerobic respiration

Answer 20

Stored chemical energy is transformed into kinetic energy and heat

Question 21

What does reparation do to the entropy of a ecosystem

Answer 21

During respiration, large amounts of energy are dissipated as heat, increasing the entropy in the ecosystem while enabling the organisms to maintain relatively low entropy/high organisation

Question 22

What are trophies levels

Answer 22

The trophic level is the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same positions in a food chain

Question 23

What are the 5 trophies levels

Answer 23

1. Producers
2. Primary consumers
3. secondary consumers
4. Tertiary consumers
5. Quaternary consumers

Question 24

What organisms are found in tropic level 1

Answer 24

Plants and algae – produce their own biomass using energy from sunlight

Question 25

What organisms are found in tropic level 2

Answer 25

Herbivores – feed on producers

Question 26

What organisms are found in tropic level 3

Answer 26

Predators – feed on primary consumers

Question 27

What organisms are found in tropic level 4

Answer 27

Predators – feed on secondary consumers

Question 28

What organisms are found in tropic level 5

Answer 28

Predators - feed on tertiary consumers

Question 29

What are producers

Answer 29

Producers (autotrophs) are typically plants or algae and produce their own food using photosynthesis and form the first trophic level in a food chain
Exceptions include chemosynthetic organisms that produce food without sunlight

Question 30

How is chemical energy transferred to primary consumers

Answer 30

The chemical energy stored in producers is then transferred to primary consumers as they consume (eat) producers

Question 31

How can the chemical energy be transfered for apex chemical after they die

Answer 31

Apex predators are at the very top of the food chain – they are carnivores with no predators
The chemical energy stored within apex predators can be passed on to decomposers when apex predators die and are decomposed

Question 32

What are feeding relationships

Answer 32

Feeding relationships involve producers, consumers and decomposers
These can be modelled using food chains, food webs and ecological pyramids

Question 33

What are decomposers

Answer 33

The net primary production (i.e. the chemical energy) of producers is also available to another group of organisms known as decomposers

Question 34

What are the 2 main groups of decomposers

Answer 34

Bacteria and fungi

Question 35

What is the role of decomposers in the ecosystem

Answer 35

They break down dead plant and animal material

Question 36

How do decomposers break things down

Answer 36

• Secreting digestive enzymes onto the surface of the dead organism
• These enzymes break down the dead matter into small soluble food molecules
• These molecules are then absorbed by the decomposers

Question 37

What is the other benefit of decomposing

Answer 37

This process of decomposition also helps to release organic nutrients back into the environment (e.g. the soil), which are essential for the growth of plants and other producers

Question 38

What are the three ecological pyramids

Answer 38

• pyramid of numbers
• pyramid of biomass
• pyramid of productivity

Question 39

What does a pyramid of numbers show

Answer 39

They are quantitative models usually measured for a given time and area

A pyramid of numbers shows how many organisms we are talking about at each level of a food chain

The width of the box indicates the number of organisms at that trophic level

Question 40

What is a pyramid of biomass

Answer 40

A pyramid of biomass measures the amount of biomass present at each trophic level at a specific point in time and represents the standing stock of each trophic level

Question 41

What is a pyramid of productivity

Answer 41

Pyramids of productivity show the flow of energy through trophic levels, indicating the rate at which that energy is being generated

Pyramids of productivity illustrate the amount of energy or biomass of organisms at each trophic level per unit area per unit time

Question 42

What is bioaccumulation

Answer 42

Bioaccumulation is the build-up of persistent or non-biodegradable pollutants within an organism or trophic level because they cannot be broken down
This means that organisms at higher trophic levels (such as top predators) may accumulate higher concentrations of pollutants than those at lower trophic levels

Question 43

What is biomagnification

Answer 43

Biomagnification is the increase in the concentration of persistent or non-biodegradable pollutants along a food chain
As pollutants are passed up the food chain from one trophic level to the next, they can become more concentrated due to the decrease in total biomass of organisms at higher trophic levels