Ecology and evolution

Question 1

Define species

Answer 1

group of same organsisms that can interbreed and produce fertile offspring

Question 2

Define habitat

Answer 2

place/environment where an organism normally lives

Question 3

Define population

Answer 3

all the members of a species in a certain area at the same time

Question 4

Define community

Answer 4

all of the populations living and interacting in an area

Question 5

Define ecosystem

Answer 5

a community and its abiotic environment

Question 6

Define ecology

Answer 6

the study of living organisms in their environment

Question 7

Distinguish between autotroph and heterotroph

Answer 7

• Autotroph is an organism that synthesize its organic molecules from simple inorganic substances. (Plants, photosynthesis, producers, self-feeding)
• Heterotroph is an organism that obtains organic molecules from other organisms (animals and any other organism incapable of making glucose from inorganic substances)
• Need to obtain sugars by eating and digesting other organisms. (Cell respiration, all consumers)

Question 8

Distinguish between consumers, detritivores and saprotrophs

Answer 8

• Consumer is an organism that ingests other organic matter that is living or recently killed. (Always heterotrophs, herbivores=planteaters, cornivores= fox, wolf, cat…)
• Detritivores: an organism that ingests non-living organic matter (heterotrophs that feed and decompose dead organic matter)
• Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion. (Fungi, Mould)

Question 9

Describe what is meant by a food chain, giving 3 examples, each with at least three linkages (four organisms)

Answer 9

Grass - grasshopper - snake - hawk - fungi

The grass makes glucose through sunlight and water, which makes grass the producer. The grasshopper eats the grass to get energy, which make him the primary consumer. The snake eats the grasshopper, which makes him the secondary consumer. The hawk eats the snake, which makes the hawk tertiary consumer.

Question 10

Describe what is meant by a food web

Answer 10

• Built of food chains which contain members belonging to more than one food chain
• Consists of interconnecting food chains
• Food webs show qualitative relationships only. (who eats who)

Question 11

Define trophic level

Answer 11

feeding level

Question 12

Deduce the trophic level of organisms in a food chain and a food web

Answer 12

1. Producer
2. primary consumer
3. secondary consumer
4. tertiary consumer
5. quaternary consumer
6. quintinary consumer

Question 13

Explain the energy flow in a food chain

Answer 13

• Energy is transferred between each trophic level
• Green plants transfer light energy into chemical energy in sugars through photosynthesis
• Energy is transferred every time a plant is eaten by a herbivore
• When a plant dies, the remaining energy passes on to detritivores and saprotrophs

Question 14

State that energy transformations are never 100% efficient

Answer 14

The only energy transferred from one step to the next is metabolites (Carbohydrates, fats, proteins) used in growth and development of the plant/animal. Around 10% of the energy is transferred. The rest of the energy goes to heat lost in space. Some food cannot be digested, and is lost, and much food is used to provide energy.

Question 15

Explain reasons for the shape of pyramids of energy

Answer 15

3 kinds

1. Pyramids of number: all organisms at each trophic level within a given area is counted
2. Pyramids of energy: based on the inflow of energy at each level
3. Pyramids of biomass: numbers x biomass (dryweight)

Question 16

Explain that energy enters and leaves ecosystems, but nutrients must be recycled

Answer 16

• Nutrients are chemical elements that make up all biochemical molecules
• They must be recycled because many are available in limited amounts
• Decomposers release nutrients from dead organisms.
• Nutrients released can then be reabsorbed by plants (Biogeochemical cycle)

Question 17

State that saprotrophic bacteria and fungi recycle nutrients

Answer 17

Energy is constantly arriving from the sun, passing through living organisms, and ultimately leaving as heat. Matter cycle between living and non-living systems, none enters and none leaves.