Paper 1 - Ecology and the Environment

Question 1

What are tertiary consumers?

Answer 1

• Animals that eat the secondary consumer
• Apex predator

Question 2

How can pH level and mineral content affect the population size and distribution of organisms?

Answer 2

• Many plants cannot grow on soil that is too acidic or alkaline
• Plants also need minerals such as nitrates to make amino acids for growth

Question 3

What are decomposers?

Answer 3

Organisms that decay dead material and help recycle nutrients

Question 4

What are producers?

Answer 4

Green plants that make their own food and energy through photosynthesis

Question 5

What are primary consumers?

Answer 5

• Animals that eat the producers
• Herbivores

Question 6

Why is only 10% of energy transferred from 1 trophic level to another?

Answer 6

• Energy is lost through respiration as heat
• Energy is lost via movement
• Energy is lost via growth
• Energy is lost via excretion as heat
• Energy is lost when not all of the biomass is consumed
• Energy is lost when not all nutrients are absorbed
• Energy is lost as parts like bones cannot be digested

Question 7

How can wind speed or direction affect population size or distribution of organisms?

Answer 7

• Changes in wind speed/direction can cause plants to lose water
• Which will decrease the population of that plant

Question 8

How can temperature affect population size or distribution of organisms?

Answer 8

• Changes in temperature can cause animals to migrate
• Plant species may die and disappear from that area

Question 9

What is meant by the term : population?

Answer 9

All the organisms of one species in a habitat

Question 10

How can water affect the population size of distribution of organisms?

Answer 10

• Low levels of water mean that animals and plants don’t have enough so they become dehydrated and die
• Animals may leave that area in search of more water

Question 11

What is meant by the term : ecosystem?

Answer 11

All the organisms living in a particular area and all the non-living conditions

Question 12

How are substances and energy transfered along a food chain?

Answer 12

• In a food chain, energy is transferred when a predator consumes its prey
• Energy is also recycled when a dead organism is broken down by decomposers

Question 13

Describe the stages of the Carbon Cycle

Answer 13

CO2 in the atmosphere
→
Plants (glucose is produced by photosynthesis)
→
Animals (Glucose is assimilated when animals feed)
→
Fossil fuels (Over millions of years, dead plants and animals are converted into fossils)
→
Decomposers (fungi or bacteria)
→
CO2 in the atmosphere

Question 14

What is meant by the term : habitat?

Answer 14

A place where an organism lives

Question 15

What are secondary consumers?

Answer 15

• Animals that eat the primary consumer (herbivore)
• Carnivores

Question 16

How could light intensity affect the population size or distribution of organisms?

Answer 16

• All plants need light to carry out photosynthesis
• If light intensity falls, the rate of photosynthesis will fall and plants will grow more slowly
• So there are fewer plants so herbivores have less food
• There are now fewer plants and fewer herbivores

Question 17

How can CO2 and O2 concentrations affect the population size or distribution of organisms?

Answer 17

• CO2 is needed for photosynthesis
• If CO2 levels fall, the rate of photosynthesis falls
• O2 is needed for aerobic respiration
• If dissolved O2 levels in water fall on a hot day, aquatic organisms like fish can die

Question 18

What is meant by the term : community?

Answer 18

All the different species in a habitat