StemUp: OCR A A level Biology 4.2.1 Biodiversity

What is biodiversity? (1)

The variety of living organisms in an area

What is a species? (1)

A group of similar organisms capable of reproducing to give fertile offspring

What is a habitat? (3)

- The area inhabited by a species

- Including physical factors (e.g., temperature, soil)

- and biotic factors (e.g., availability of food)

What are the different levels at which biodiversity can be considered? (3)

- Habitat diversity: Number of different habitats in an area

- Species diversity: Number of different species and the abundance of each

- Genetic diversity: Variation of alleles within a species

How is sampling used to measure biodiversity in a habitat? (2)

- Sampling is used to estimate species richness and species evenness

- It can be random or non-random (systematic, opportunistic, or stratified)

What is random sampling, and why is it important? (2)

- Random sampling avoids bias by selecting random coordinates within an area

- Ensuring an unbiased estimate of biodiversity

What are the three types of non-random sampling? (3)

- Systematic: Samples taken at fixed intervals along a transect

- Opportunistic: Samples chosen by the investigator, though data may be biased

- Stratified: Different areas are sampled separately in proportion to their size.

How is the capture-recapture method used to estimate population size? (3)

1. Capture a sample, mark them, and release them

2. Recapture a second sample after some time

3. Estimate population size using the formula

What is the capture-recapture formula? (3)

How are species richness and evenness measured? (2)

- Species richness: Number of different species in an area

- Species evenness: Relative abundance of different species

What is Simpson's Index of Diversity? (1)

Measures biodiversity considering species richness and evenness

How is Simpson's Index of Diversity calculated? (4)

What is genetic diversity? (1)

The variation of alleles within a species

Why is genetic diversity important? (2)

- Important for populations to adapt to environmental changes

- And to avoid extinction due to low diversity

What are genetic polymorphisms and how are they used to measure genetic diversity? (2)

- Polymorphism = a locus that has 2 or more alleles

- Working out the proportion of polymorphic gene loci in an organisms gives a measure of genetic diversity

How does human population growth affect habitats? (2)

- Human development (e.g., deforestation for agriculture) destroys habitats

- Decreasing biodiversity

What is overexploitation, and how does it affect biodiversity? (2)

- Overexploitation is the use of resources faster than they can be replenished (e.g., overfishing)

- Leading to a decrease in genetic diversity and species extinction

How does urbanisation affect biodiversity? (2)

- Urbanisation (e.g., road and city development) can isolate species

- Preventing interbreeding and reducing genetic diversity

How does pollution affect biodiversity? (2)

- Pollution kills species and destroys habitats

- Decreasing biodiversity

How does monoculture affect biodiversity? (3)

- Monoculture (growing one type of crop) reduces habitat diversity by clearing land

- Herbicides/pesticides kill local plants and animals

- Reducing species diversity

How does monoculture affect heritage varieties of crops? (2)

- Heritage varieties of crops are often not planted due to low economic returns

- Reducing species diversity

What is climate change, and what causes it? (2)

- Variation in Earth's climate (e.g., temperature, rainfall)

- It occurs naturally and due to human activities, such as increased greenhouse gas emissions

What is global warming, and what causes it? (2)

- Global warming is the increase in the Earth's average temperature

- Caused by the buildup of greenhouse gases like CO2

How does climate change affect species survival? (3)

- Many species require specific climates to survive

- Changes in climate can make previously inhabitable areas uninhabitable

- Leading to reduced biodiversity

How does climate change affect species migration? (3)

- Climate change may force species to migrate to more suitable habitats

- Changing species distribution

- Affecting biodiversity in both the original and new areas

How can climate change lead to species extinction? (3)

- If a species cannot migrate to a suitable habitat or the change occurs too quickly

- the species may become extinct

- Decreasing biodiversity

What is an ecosystem? (2)

- Includes all the living organisms in a particular environment

- and all the non-living conditions (e.g., climate, soil, water)

Why is it important to protect species in an ecosystem? (3)

- Species in an ecosystem are interdependent

- Meaning the loss of one species can disrupt food chains and nutrient cycles

- Affecting other species

What can happen if a species is lost from an ecosystem? (3)

- Loss of a species can disrupt food chains and nutrient cycles

- For example, a decline in decomposers like worms can reduce soil quality and affect plant growth

- Which in turn affects animals that depend on those plants

What is a keystone species? (2)

- A species on which many other species in an ecosystem depend

- Without it, the ecosystem would undergo dramatic changes

What is an example of a keystone species and its role in an ecosystem? (3)

- The wolf in America

- When wolves were eliminated, elk populations increased, leading to overgrazing and loss of plant species

- Which affected other species like beavers

What are the roles of different keystone species? (3)

1. Predators: Control prey populations (e.g., wolves)

2. Modifiers: Maintain the environment (e.g., beavers building dams).

3. Hosts: Provide a specific environment for other species (e.g., palm trees).

What are genetic resources, and why must they be conserved? (3)

- Materials from plants, animals, and microorganisms that contain valuable genes

- E.g., crops, medicines, renewable fuels

- They must be conserved to provide essential products and adapt to environmental changes

What are some everyday products derived from genetic resources? (3)

- Food, fibres for clothing, medicines (e.g., morphine from poppies)

- Renewable fuels (e.g., biogas)

- Materials like wood, paper, and rubber

How can genetic resources help humans adapt to climate change? (3)

- Genetic resources allow us to genetically engineer plants

- E.g. for resistance to drought or other environmental changes

- Helping to adapt to climate change

How does monoculture lead to soil depletion? (2)

- Continuous monoculture depletes the soil of nutrients

- Leading to reduced yields and the need for artificial fertilisers

How do traditional farming methods prevent soil depletion? (2)

- Traditional farming methods prevent soil depletion by rotating crops

- Which helps replace nutrients and organic matter in the soil

Why is biodiversity important from an aesthetic perspective? (2)

- Areas rich in biodiversity are more visually attractive

- Leading to economic advantages by attracting more visitors

What is in situ conservation? (1)

Involves protecting species in their natural habitat

What are some methods used in in situ conservation? (5)

1. Establishing protected areas (e.g., national parks, wildlife reserves)

2. Marine Conservation Zones

3. Controlling non-native species,

4. Protecting habitats (e.g., coppicing)

5. Providing legal protection for endangered species

What are the advantages of in situ conservation? (4)

- Conserves both species and habitats

- Larger populations can be protected

- Less disruptive than removing species

- Greater chance of population recovery.

What is a disadvantage of in situ conservation? (2)

- Difficult to prevent external factors

- E.g. Poaching, predators, disease, and climate change

What is ex situ conservation? (2)

- involves removing part of a population from its threatened habitat

- And placing it in a new, controlled location

What are some methods used in ex situ conservation? (4)

1. Relocation to safer areas

2. Breeding in captivity (e.g., zoos, animal sanctuaries)

3. Botanical gardens

4. Seed banks

What are the advantages of ex situ conservation? (2)

- Controlled environment makes it easier to manage predation and hunting

- Can reintroduce species into the wild

What are the disadvantages of ex situ conservation? (4)

- Only a small number of individuals can be cared for

- Expensive and difficult to maintain the right environment

- Animals habituated to human contact may not exhibit natural behaviour or may catch diseases

- Many species struggle to breed in captivity or adapt to new environments

What is the purpose of the Rio Convention on Biological Diversity (CBD)? (2)

- To develop international strategies for conserving biodiversity and using plant/animal resources sustainably

- It made biodiversity conservation everyone's responsibility and provides guidance to governments

What is the CITES agreement, and how does it help conserve biodiversity? (3)

- The Convention on International Trade in Endangered Species regulates trade in wild animal and plant specimens

- It makes it illegal to kill endangered species and limits trade in products like ivory

- It also raises awareness of biodiversity threats

What is the Countryside Stewardship Scheme, and how does it help biodiversity? (2)

- It aims to conserve wildlife and biodiversity by promoting management techniques to landowners

- E.g., regeneration of hedgerows, leaving grassy margins