B17, B18, B19

B17 - Variation & selection

100

What term describes the observable features of an organism?

A Phenotype.

200

Define Mutation

A genetic change.

300

Explain 2 differences between Natural selection and selective breeding.

- Environmental factor vs human chosen

- Purpose: survival vs produce traits useful to humans

- Speed: slow vs fast

- Genetic diversity: maintained vs reduced (due to human selection)

400

Contrast Discontinuous and continuous variation with examples.

Discontinuous:

- Limited phenotypes, no intermediates (eye colour, blood groups, seed colour)

Continuous: 

- A range of phenotypes (Height, body mass, Leaf surface area)

500

Explain how antibiotic resistant bacteria are created.

1. Bacteria reproduces

2. Genetic mutated bacteria appears

3. When antibiotic is used, it kills the normal bacteria but the genetic mutated bacteria survives.

4. The genetic mutated bacteria begins to reproduce.

5. Antibiotic no longer is effective.

B18 - Energy & Cycles, food webs

100

What process do plants use the sun to do?

Photosynthesis

200

What is the principal source of energy for most ecosystems?

Sun

300

How efficient is energy passed on from one trophic level to another? And how is it eventually lost?

- 10% passed on. 

- Eventual loss through heat energy.

400

Define the term "Decomposer" and explain why they are not usually given a specific trophic level in a simple food chain. 

- Gets its energy from dead or waste organic matter. 

- Because they feed on dead organisms from all trophic levels.

500

Use the concept of energy transfer to explain why the number of organisms usually decreases as you move up a food chain.

- Energy is lost at each level (via heat from respiration, waste, or uneaten parts). 

- Less energy available

- Cannot support a large number of individuals at higher trophic levels.

B18 - Carbon cycle

100

State the word equation of photosynthesis.

Carbon dioxide + water -> Glucose + Oxygen

200

What is the carbon cycle?

Describes how carbon moves through the environment.

300

How much % of Earth's atmosphere is composed of CO2? Bonus 200 pts for composition of inspired & expired air (optional).

0.04%

Bonus:

Oxygen - 21% inspired, 16% expired

Nitrogen - 78% inspired, 78% expired

CO2 - 0.04% inspired, 4% expired

Other gases - 1% inspired, 2% expired

400

State the 4 main reservoirs carbon is stored in.

Carbon is stored and cycles between four main reservoirs:

• the atmosphere
• oceans
• land biomass
• fossil fuels

500

Label the carbon cycle:

• 1: Combustion

• 2: Feeding

• 3: Solar energy / Sunlight

• 4: Carbon dioxide in atmosphere

• 5: Respiration (Animal)

• 6: Decomposition

• 7: Fossil fuels

• 8: Respiration (Plant)

• 9: Fossilization

• 10: Death and waste

• 11: Photosynthesis

B19 - Habitat destruction

100

Describe biodiversity

the number of different species that live in an area

200

Describe an ecosystem

a unit containing the community of organisms and their environment, interacting together

300

Name two reasons for habitat destruction.

(a) increased area for housing, crop plant production and livestock production

(b) extraction of natural resources 

(c) freshwater and marine pollution

400

List 4 undesirable effects of deforestation

reducing biodiversity

extinction

loss of soil

flooding

increase of carbon dioxide in the atmosphere

500

Explain the undesired effects of deforestation

• Reducing biodiversity: Deforestation destroys habitats, causing many species to lose their homes and reducing the variety of life in the area.

• Extinction: Some species cannot survive without their forest habitat and may die out completely when it is removed.

• Loss of soil: Without tree roots to hold it in place, soil is easily eroded by wind and rain.

• Flooding: The removal of trees reduces water absorption, causing more surface runoff and increasing the risk of floods.

• Increase of carbon dioxide in the atmosphere: Cutting and burning trees reduces carbon dioxide absorption and releases stored carbon, raising atmospheric CO₂ levels.

B19 - Conservation

100

What is hunting?

This cause of endangerment happens when animals are killed by humans for food, sport, or trade.

200

What is pollution?

This occurs when harmful substances enter ecosystems and damage living organisms.

300

What is habitat destruction?

This cause of extinction happens when environments are destroyed, such as through deforestation.

400

What are captive breeding programmes?

This conservation method involves breeding endangered species in controlled environments to increase their population.

500

What are introduced species?

This happens when non-native species are introduced and outcompete or prey on native organisms, causing their decline.