Classification & Biodiversity (WJEC GCSE Science (Double Award): Biology): Flashcards

Animals with a backbone are called vertebrates.

The scientific name of a species is made up of its genus and its species.

True.

Mosses and ferns are non-flowering plants because they do not produce flowers.

False.

Appearance alone can be misleading. DNA analysis gives a more reliable picture of how closely species are related.

Older names could be extremely long and unwieldy.

A two-part name is short and simple, allowing easy identification.

A feature of an organism that aids its survival in its environment.

A physical feature of an organism that aids its survival.

Something an organism does that aids its survival.

They reduce heat loss to the very cold environment, helping the fox maintain its body temperature.

Spines give a much reduced leaf surface area, so less water is lost by transpiration in a dry desert environment.

It improves swimming efficiency, so the dolphin can move faster and use less energy.

Staying in underground burrows during the heat of the day prevents them from overheating and losing too much water.

There is an increased chance of catching prey, so the pride is more likely to have enough food.

A morphological adaptation is a physical feature of an organism that aids survival.

Hunting in groups is an example of a behavioural adaptation.

False.

Huddling is something the penguin does, so it is a behavioural adaptation.

False.

You must state the feature and then explain how it aids survival. Many marks are lost by omitting the explanation.

The large surface area allows more heat to be lost to the surroundings, helping the fox stay cool in a hot environment.

State the feature, then explain how it aids survival in that particular environment.

• Food

• Water

• Mates

• Territory containing those resources

• Water

• Light

• Minerals

• Space to grow

Competition for resources between individuals of the same species.

Competition for resources between individuals of different species.

Competition for resources, whether within a species or with another species, limits the maximum size the population can reach.

Predators increase the death rate, slowing population growth.

A lack of predators may allow a population to grow rapidly.

Infection spreads more quickly between individuals in crowded conditions.

Pollution can kill individuals directly and alter the structure of the ecosystem, e.g. by removing a species' food source or its predators.

Competition between grey squirrels and red squirrels is an example of interspecific competition.

Competition between individual grey squirrels for the same food is an example of intraspecific competition.

False.

It may grow rapidly at first, but competition for resources and disease will eventually limit its size.

False.

They also compete with different species that need the same resources. This is interspecific competition.

• Competition

• Predation

• Disease

• Pollution

Heavy metals accumulate most in top predators.

If predator numbers fall as a result, there is less predation, so the prey population can increase.

The variety of different species and the numbers of individuals within those species in an area.

By measuring:

• The number of different species present

• The number of individuals of each species

Many species interact, so no single species depends entirely on one other.

If one species declines, others can take its place in the food web.

Any three of:

• A plentiful and reliable food supply

• A reliable supply of biological resources, e.g. timber

• Potential medicines are not lost before being discovered

• Well-being benefits of spending time in nature

The Convention on International Trade in Endangered Species.

It is an agreement between governments to prevent the capture and sale of endangered plant and animal species.

They are protected areas in which human activities are regulated, protecting the species and ecosystems inside their borders.

Zoos carry out carefully controlled breeding to increase numbers while maintaining genetic health.

Offspring may stay in the programme or be released into the wild.

A store of seeds from many plant species kept under carefully controlled conditions.

It means plant species can be saved even if their natural habitats are lost.

To identify at-risk species in an area and set out the steps needed to protect them and their habitats.

Biodiversity is the variety of different species and the numbers of individuals within them in an area.

Sperm banks store the sex cells of endangered animals to protect their genetic material.

True.

Both the number of species and the evenness of their numbers contribute to biodiversity.

True.

An increasing human population and its demand for resources is putting biodiversity worldwide under pressure.

The predators have other food sources available.

This is why a food web with many species is resilient to change.

Laws must be enforced to work, which is difficult and costly across international borders.

Restrictions may also conflict with local people's livelihoods or a country's economic development.

The process of collecting a series of small data sets that can be used to represent an entire population.

• Abundance: how many organisms or species are present

• Distribution: where a species is found within the habitat

In large and complex habitats it is not possible to find, identify and count every organism present.

• Sample sites must be chosen randomly, to avoid bias

• Enough samples must be taken; more samples give more representative results

A square frame placed within an area being studied in order to take a sample.

Lay out two tape measures at the edges of the habitat like a pair of graph axes to create a grid.

Use a random number generator to choose two numbers as grid coordinates.

Place the quadrat at that point and take a measure of abundance. Repeat many times.

To avoid bias, e.g. a student choosing a spot where the organisms look easier to count.

• The number of species within the quadrat

• The number of individuals of a particular species

• The percentage cover of a species

When individual organisms cannot easily be distinguished, for example grass.

A line laid out across a habitat, used to measure the effect of an environmental factor on distribution along a gradient.

Lay a tape measure across the habitat along the chosen gradient.

Place the quadrat at set intervals, e.g. every 1 or 5 metres.

Take a measure of abundance at each point, and repeat to get a representative sample.

Quadrats should be placed randomly within a habitat to avoid bias.

A transect is used to study the distribution of organisms along an environmental gradient.

False.

Quadrat size depends on the organisms studied. A 1 m² quadrat suits small plants, while a 400 m² quadrat may be used for trees.

True.

A larger number of samples is more likely to reflect the habitat as a whole, making conclusions more valid.

Quadrats only work for sessile organisms that stay in one place.

Capture/recapture is used to estimate the population of motile animals that move around.

Capture a sample of the population and mark each animal using a non-harmful method.

Release them and allow time for them to mix with the rest of the population.

Capture a second sample and count how many are marked and unmarked.

Use the equation to estimate the population size.

N = (n₁ × n₂) ÷ m₂

• N = population estimate

• n₁ = number marked and released in the first sample

• n₂ = total number in the second sample

• m₂ = number of marked individuals in the second sample

N = (236 × 244) ÷ 71

N = 57 584 ÷ 71

N = 811

So they have time to mix evenly with the rest of the population, otherwise the second sample would not be representative.

• The population stays the same size during the study, with no births, deaths or migration

• The marking does not affect survival, e.g. by making individuals easier for predators to see

So the marking does not change the animal's chance of survival, which would make the population estimate invalid.

Capture/recapture is used to estimate the population size of motile animals.

Capture/recapture is also known as the mark-release-capture technique.

True.

The method assumes the population stays the same size between the two samples. Births, deaths or migration would make the estimate unreliable.

True.

A small proportion of marked animals means the marked individuals are diluted among many unmarked ones, so the population must be large.

Fewer marked animals would be recaptured, making m₂ smaller.

Dividing by a smaller number gives a larger population estimate than the true value.

A small amount of non-toxic waterproof paint applied to the underside of the animal.

Any three of:

• Light intensity

• Competition from other species

• The presence of a feature such as a road or stream

• Disturbance, e.g. grazing or mowing

Lay two tape measures at right angles on the mowed area to create grid axes.

Use a random number generator for two grid coordinates and place a 1 m² quadrat there.

Count the daisies in the quadrat, then repeat for at least 10 quadrats.

Repeat the whole process on an unmowed section and compare the estimates.

To ensure sample sites are chosen at random, which avoids bias and makes the results more likely to represent the area accurately.

Include plants that fall more than half within the quadrat.

Population estimate = number of individuals in sample × (total area ÷ sample area)

Population estimate = 56 × (400 ÷ 15)

Population estimate = 1 493.3

Population estimate = 1 493 daisies

• Independent variable: whether or not the field has been mowed

• Dependent variable: the estimated daisy population for each field

Any three of:

• Time of year the samples are collected

• Soil type

• Light intensity

• Level of disturbance, e.g. from students using the field

A larger number of samples is more representative of the whole area, making any conclusion drawn from the data valid.

Use a field identification guide to recognise the shape of the leaves.

• Hazard: plant thorns and stings

• Risk: cuts or stings to the skin

• Control measure: avoid touching plants while counting and learn to identify harmful species

A 1 m² quadrat is used to sample the daisies at each grid coordinate.

True.

Factors such as soil type and light intensity cannot always be controlled, so their possible effect must be considered when drawing conclusions.

False.

Choosing by eye introduces bias. Quadrat positions must be chosen using random coordinates.

A living organism used to limit the population of a pest species, keeping its numbers to a minimum.

• Predators

• Parasites

• Pathogens

It reduces reliance on chemical pesticides, which cause pollution and toxicity in food chains.

They lay their eggs inside the bodies of the pest species.

The pests die when the wasp eggs hatch, reducing the pest population.

A species introduced to a region where it does not naturally occur. Also known as an invasive species.

• Deliberately by humans, e.g. as a pet or garden plant

• Accidentally, e.g. travelling attached to the hull of a ship

Cane toads are toxic, so they poison native predators that eat them.

The lack of suitable predators meant their population exploded.

The Asian species is more aggressive and will prey on the native species.

It grows fast and outcompetes native plants for light and space.

Its fallen leaves also produce leaf litter that is toxic to many other species.

To check their effect on non-target native species, and to work out how the agent itself could be controlled if problems arise.

A species introduced to a region where it does not naturally occur is called an alien species.

Biological control agents are living organisms used to limit the population of a pest species.

True.

It was introduced in the 1930s to control pests, but became a serious invasive species itself.

False.

It avoids chemical pollution, but a poorly researched control agent can become an invasive species and cause serious ecological harm.

It has no natural predators there and may outcompete native species for food, light or space.