B2 - Understanding Our Environment

Question 1

What classifies a group of animals as a species?

Answer 1

A group of animals that are capable of interbreeding to produce fertile offspring.

Question 2

List all items on the classification tree from the widest group to the narrowest.

Answer 2

Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 3

How is the binomial system used?

Answer 3

All species are given a two-part name. The first part refers to the genus, the second part refers to the species.

Question 4

Why are pyramids of biomass always pyramid-shaped?

Answer 4

Energy is lost at each trophic level, resulting in a drop in biomass as you move up the food chain.

Question 5

How is energy lost from one trophic level to the next?

Answer 5

• Excretion of food that can’t be digested.
• Movement
• Energy consumed to produce heat, which is eventually lost to surroundings.

Question 6

How do you calculate the efficiency of an energy transfer between two trophic levels?

Answer 6

Efficiency = Energy available to next level / Energy that was available to previous level

Question 7

What is an ecological niche?

Answer 7

The role that a species occupies within an ecosystem - i.e. its habitat and the food it feeds on.

Question 8

What is interspecific competition?

Answer 8

Organisms compete for resources against individuals from another species.

Question 9

What is intraspecific competition?

Answer 9

Organisms compete for resources against individuals of the same species.

Question 10

Why does intraspecific tend to have a greater impact on an organism than interspecific competition?

Answer 10

If competing against members of the same species, the organism will be competing against other organisms within its own ecological niche. As a result, they’ll all be competing for the same limited resources.

Question 11

Why are predator-prey cycles out of phase?

Answer 11

When the number of prey increases, more food is available for the predators to reproduce. While the predator population will eventually increase as a result of an increase in the prey population, this doesn’t happen immedietely as it takes time for reproduction to occur.

This is why there is a ‘lag’ between the increase in the population of one species and the effect that has on the other species.

Question 12

What is a parasitic relationship?

Answer 12

A parasite takes things from the host without giving anything back. In the process, the host can be harmed.

Question 13

What is a mutualistic relationship?

Answer 13

Two organisms benefit from eachother’s actions.

Question 14

What is a specialist organism?

Answer 14

An organism highly-adapted for a specific habitat. For example, giant pandas are adapted to eat just bamboo.

Question 15

What is a generalist organism?

Answer 15

An organism that is adapted to survive in a range of different habitats. for example, black rats can survive in forests, cities and farmland.

Question 16

What is an extremophile?

Answer 16

An organism adapted to tolerate extreme conditions such as really high or low temperatures.

Question 17

What are anatomical adaptations?

Answer 17

Features of an organism’s body structure that help it to survive.

Question 18

Why are some animals adapted to have a small surface area to volume ratio in cold environments?

Answer 18

If an organism has a smaller surface area to volume ratio, less of its body is in contact with the outside. As a result, less heat is able to be transferred out of the organism’s body. Therefore, heat loss is reduced.

Question 19

Explain how counter-current heat exchange systems help maintain body temperatures in cold conditions?

Answer 19

In a penguin’s foot, the arteries and veins pass near each other. As a result, the cool blood returning from the vein is heated up by the warmer blood flowing in the arteries.

While their feet stay cold, the returning blood is warmed up - preventing colder blood from cooling down the rest of the body.

Question 20

List behavioural adaptations that allow animals to survive in cold environments.

Answer 20

• Species huddle together to keep warm.
• Species migrate to warmer climates during winter.
• Species hibernate during winter

Question 21

What needs to be achieved for animals to survive in hot environments?

Answer 21

• Heat loss needs to be increased.

- Heat gain needs to be reduced.

Question 22

List behavioural adaptations that allow animals to survive in hot environments.

Answer 22

• Spend the day in the shade or underground.
• Sleeping during day, working during night.
• Bathing in water; as the water evaporates, energy transferred from animal’s skin into the surroundings.

Question 23

How are animals anatomically adapted to survive in hot environments?

Answer 23

They have a large surface area to volume ratio, meaning that a large portion of their body is in direct contact with the surroundings. As a result, more heat is lost.

Question 24

How do big thin ears help increase heat loss?

Answer 24

• Increased surface area to volume ratio.

- Blood flows closer to the surface of the skin, meaning more heat is radiated from the blood to the surroundings.

Question 25

How are desert animals adapted?

Answer 25

• Special kidneys, allowing them to produce highly concentrated urine with low water content.
• No sweat glands.
• Lots of time spent underground.

Question 26

How are desert plants adapted?

Answer 26

• Rounded shape for small surface area to volume ratio (minimising water loss).
• Waxy cuticle instead of leaves to reduce water loss.
• Water stored in stems.
• Shallow but extensive roots to ensure water is absorbed quickly over large area.

Question 27

Explain the ‘survival of the fittest’ theorised by Darwin.

Answer 27

• Wide natural variation exists among organisms.
• Some organisms are better adapted than others.
• The well-adapted organism more likely to reproduce and share their adaptations with their offspring.
• Overtime, the successful adaptations become more common and the species changes (evolves).

Question 28

How can evolution lead to the creation of an entirely new species?

Answer 28

If a species become physically separated into multiple groups, the natural selection of different mutations in each of the groups eventually leads to extreme differences between the characteristics of each group.

Eventually, this means the different groups can no longer interbreed (become reproductively isolated). As a result, the different groups will be different species.

Question 29

Why is decomposition slower in waterlogged and acidic soils?

Answer 29

In waterlogged soils, there is less oxygen - therefore, the decomposers have less energy and work more slowly.

In acidic soils, the reproduction of decomposers slows down - if extremely acidic, the decomposers might even die.

Question 30

Describe the carbon cycle.

Answer 30

• CO2 in the air enters plants via photosynthesis.
• Animals eat plants, and absorb carbon compounds.
• When animals die, they decay and decomposers release CO2 via respiration.
• Carbon compounds from dead animals and plants are decayed by the soil over millions of years, and form fossil fuels.
• These fuels are burnt, with combustion releasing CO2 back into the atmosphere.

Question 31

Describe the nitrogen cycle.

Answer 31

• Decomposers break down proteins proteins and urea into ammonia. Ammonia is put into soil.
• Nitrifying bacteria converts ammonia into nitrates.
• Plants absorb nitrates and build proteins.
• Plants die and the cycle continues.
• Nitrogen-fixing bacteria turns nitrogen gas into nitrogen compounds that plants can use.
• Denitrifying bacteria turns nitrates back into nitrogen gas.
• Lightning can cause nitrogen to react with oxygen to produce nitrates.

Question 32

Describe the environmental of increasing pollution.

Answer 32

Acid rain caused by sulfur dioxide:

• Acidic lakes/rivers, fish die.
• Soil becomes acidic/trees damaged.

Global warming, greenhouse effect.

Harmful UV rays are killing plankton in the oceans as a result of the depletion of the ozone layer (caused by CFCs). This could cause fish levels to drop.

Question 33

How do we use indicator species to measure pollution?

Answer 33

Some species, such as lichen and mayfly larvae, can only survive in unpolluted conditions. As a result, if we find them in an area, the area is probably clean (not polluted).

On the other hand, species such as water lice only survive in polluted conditions. If they are present, the area is likely polluted.

Question 34

Name an advantage and disadvantage to using indicator species to measure pollution.

Answer 34

• It is quick, cheap and easy.

- Other factors may effect the population of the indicator species.

Question 35

Name an advantage and disadvantage to using abiotic methods to measure pollution?

Answer 35

• Quantitative data and exact pollutants can be identified.

- It is often more expensive and requires trained workers.

Question 36

What is genetic variation?

Answer 36

The number of different alleles (forms of a gene) in a population.

Question 37

How do we evaluate conversation programmes?

Answer 37

• Genetic variation; this is needed to cope with new diseases and environmental change.
• Interaction with other species; animals need to be able to interact with other species as they would in their natural environment.
• Viability of populations: must be able to reproduce without inbreeding (population with male and females of similar ages).
• Available habitats: the organism needs to be living in a suitable habitat, this is important for specialised organisms.

Question 38

What is sustainable development?

Answer 38

Providing for the needs of today’s increasing population without harming the environment.

Question 39

Name two examples of sustainable development.

Answer 39

1. Fishing quotas to prevent species from going extinct.

2. Logging companies plant new trees to replace those cut down.