Environmental Biology (Edexcel International A Level (IAL) Biology): Flashcards

Thermometer records from different places around the world can be put together to show average global temperature change over time.

Pollen grains from peat bogs identify which plant species grew at different times, which indicates the climate conditions at those times.

False.

Wider tree rings indicate warmer years, as trees grow faster in warmer conditions.

A greenhouse gas is a gas that absorbs radiation re-emitted from the Earth's surface and traps it in the atmosphere, preventing heat loss to space.

The greenhouse effect is important to ensure that Earth is warm enough for life.

Anthropogenic climate change is mainly caused by increased levels of greenhouse gases like carbon dioxide and methane entering the atmosphere as a result of human activities.

The two most important greenhouse gases linked to human activities are carbon dioxide and methane.

Greenhouse gases absorb radiation re-emitted from the Earth's surface, trapping heat in the atmosphere and preventing it from escaping into space.

A carbon sink is a natural store of carbon, such as trees, soils, peat bogs, or oceans, that absorbs more carbon than it releases.

False.

Correlation alone does not prove causation; other factors may also influence global temperatures.

Since the industrial revolution, atmospheric carbon dioxide levels have risen to their highest in at least 800,000 years.

Methane (CH₄) is a simple hydrocarbon gas present in the atmosphere and underground, and is the main component of natural gas fossil fuel.

Two human activities that increase methane levels are intensive cattle farming and landfill decomposition.

The carbon cycle is the series of processes by which carbon is transferred and stored between the atmosphere, living organisms, oceans, and rocks.

The process is photosynthesis, carried out by producers, which removes carbon dioxide from the atmosphere and incorporates it into their biomass.

When animals and plants respire, they release carbon dioxide back into the atmosphere.

True.

Carbon that is not fully decomposed can be stored for long periods in peat and fossil fuels.

Carbon is transferred between organisms when one consumes and digests another.

A carbon sink is a location where carbon is stored for a long period, such as peat, fossil fuels, or forests.

Increasing the rate of photosynthesis (e.g. by planting more trees) removes more carbon dioxide from the atmosphere, reducing the greenhouse effect.

Reducing the combustion of fossil fuels helps prevent further increases in atmospheric carbon dioxide.

True.

A good understanding of the carbon cycle allows us to identify points where we can reduce emissions or increase carbon removal, helping to manage atmospheric carbon dioxide levels.

Reducing the disturbance of carbon pools such as soils and peat bogs can help reduce the transfer of carbon to the atmosphere.

Extrapolating from data is using existing data to make predictions about future trends.

Climate change prediction models are limited because they are based on extrapolated data, and factors such as future human actions and technological success are unknown.

The Intergovernmental Panel on Climate Change (IPCC) uses data from around the world to extrapolate how global temperatures might change.

False.

It is impossible to know exactly which emissions scenario will occur because future human actions and technological developments are uncertain.

A tipping point is a threshold at which a small change can cause a significant and often irreversible shift in the global climate system.

Global warming predictions help society by allowing for the planning of flood defences and encouraging the development of climate change technologies.

Future technologies such as carbon capture may or may not be successful at removing greenhouse gases from the atmosphere.

Individuals can help reduce predicted global temperature increases by reducing fossil fuel use, using renewable energy, and reducing meat consumption.

Permafrost is ground that is frozen all year round.

A large volcanic eruption can increase ash in the atmosphere, reflecting radiation and potentially cooling the Earth.

Greenhouse gases are gases in the atmosphere that absorb infrared radiation emitted by the Earth, causing the atmosphere to warm.

A higher concentration of greenhouse gases in the atmosphere leads to more infrared radiation being absorbed, making the atmosphere warmer.

Hotter, longer heatwaves and more violent storms are both becoming more common as a result of climate change.

Changes to ocean currents, such as the Gulf Stream, can lead to altered local climates.

True.

There is already evidence of changes in climate patterns in many areas globally as a result of climate change.

Warming climates cause some animals to move towards the poles or to higher altitudes.

Species that rely on seasonal rains for survival, such as some desert plants, may no longer get enough water if rainfall becomes less frequent or stops altogether, threatening their survival.

Due to climate change, polar ice and glaciers are retreating, which may lead to rising sea levels.

The optimum temperature is the temperature at which an enzyme catalyses a reaction at the maximum rate.

Lower temperatures decrease the kinetic energy of molecules, resulting in a lower frequency of successful collisions and thus slowing down or preventing enzyme-catalysed reactions.

As temperature increases beyond the optimum, the rate of enzyme activity drops sharply because the enzyme begins to denature.

Enzymes become denatured at high temperatures when their tertiary structure is permanently altered and the active site is no longer complementary to the substrate.

True.

At higher temperatures, molecules move faster and collide with more energy, making bond formation or breaking more likely.

Denaturation is the permanent change in the shape of an enzyme's active site due to the breaking of bonds in its tertiary structure, preventing substrate binding.

A Q₁₀ value of 2 means the rate of reaction doubles when temperature increases by 10 °C, while a value of 3 means it trebles.

Q₁₀ is calculated by dividing the rate at the higher temperature by the rate at the lower temperature.

Higher temperatures speed up enzyme-controlled reactions up to the optimum, but temperatures above the optimum denature enzymes, slowing metabolism and reducing growth and crop yields.

False.

Some fish eggs have been shown to develop more slowly at higher temperatures, so an increase in temperature does not always speed up their development.

Global warming can affect the development of living organisms by altering environmental temperatures, which can impact their growth rates and life cycles.

A controlled variable is any factor in an experiment that is kept the same across all groups so that only the independent variable affects the results.

To study the effect of temperature on seedling growth rate, all other factors such as light intensity and soil moisture should be kept constant.

False.

Seedling growth rate increases up to 25 °C, but then decreases as higher temperatures can cause enzyme denaturation.

The average growth rate is calculated as: average change in seedling height for incubator divided by days of incubation.

Brine shrimp hatching rate is calculated as the number of hatched shrimp eggs divided by the number of hours in the water bath.

Welfare considerations include returning hatched shrimps to a suitable environment and avoiding dangerously high temperatures during the experiment.

Enzyme denaturation is the process in which a protein's structure is altered by high temperature, causing it to lose its biological activity.

Evolution is the process by which heritable characteristics of organisms change over generations, leading to the development of new species over time.

A heritable characteristic is a trait that can be passed on from parents to their offspring through their genes.

Natural selection can only take place if there is variation present in a population.

Natural selection is the process by which organisms that are better adapted to their environment are more likely to survive and reproduce, passing on advantageous alleles to their offspring.

The three main sources of variation in a population are mutation, meiosis and random fertilisation during sexual reproduction.

Alleles may change due to random mutation, making them more or less advantageous.

False.

Non-heritable characteristics are acquired during an organism's lifetime and cannot be passed on to offspring.

Environmental factors that influence survival are known as selection pressures.

A selection pressure is an environmental factor, such as predation, competition for food or disease, that affects the survival chances of organisms in a population.

The frequency of advantageous characteristics increases in a population over time as individuals with these traits are more likely to survive and reproduce.

Rabbits with brown fur are more likely to survive and reproduce due to better camouflage.

False.

Evolution occurs as a result of natural selection acting on random variation, not as a direct or purposeful response to the environment.

Individuals with unfavourable characteristics are less likely to survive and reproduce, so these characteristics become less frequent in the population.

Speciation is the development of new species from pre-existing species over time.

For speciation to occur, the two populations must be isolated from each other in some way so that there is no exchange of genes between them.

The exchange of genes between populations is known as gene flow.

Geographical isolation occurs when populations are separated by physical barriers such as mountains or rivers, preventing gene flow and leading to allopatric speciation.

Allopatric speciation is speciation that occurs as a result of geographical isolation between populations of a species.

False.

Man-made barriers, such as motorways, can also cause geographical isolation leading to allopatric speciation.

If two populations become so different that they can no longer interbreed and produce fertile offspring, speciation has occurred.

Sympatric speciation occurs without geographical barriers, often due to random mutations or changes in behaviour, timing, or mechanics that prevent interbreeding within the same habitat. This differs from allopatric speciation, which requires physical separation.

In sympatric speciation, populations are isolated in the same habitat but do not interbreed.

Natural selection is the process through which advantageous alleles increase in frequency in a population because they provide increased survival or reproductive success.

Genetic drift is the random change in allele frequencies in a population, which can contribute to speciation by causing populations to diverge genetically over time.

Over time, changing allele frequencies lead to changes in the phenotypes of the two populations.

True.

Different selection pressures can cause different alleles to become advantageous in each population, leading to genetic divergence and ultimately speciation.

A scientific consensus is a general agreement among the scientific community that a particular idea or finding is supported by strong evidence.

True.

The vast majority of scientists agree that human activities are directly responsible for the rise in greenhouse gas concentrations.

Some individuals claim that global warming is caused by factors other than human activities.

Bias is the tendency to favour a particular outcome or interpretation due to personal, financial, or political interests.

It is important because only scientific evidence can demonstrate whether claims are supported, reliable, and unbiased.

Reliable climate change data should come from several independent studies and be statistically significant.

Predictions are difficult because climate is highly complex and there may be tipping points beyond which changes happen much faster.

It is wrong because climate trends must be assessed over time, not from one event, and climate is influenced by many factors each year.

When evaluating claims about climate change, scientists must consider if the claim comes from a trustworthy and unbiased source.

A great deal of scientific evidence tested and checked by other scientists supports this claim, increasing its likelihood of being correct.

Sustainability is the practice of using the world's resources in ways that do not damage the environment and can be maintained for future generations.

Sustainability is important because it ensures that resources are available for future generations without causing long-term damage to the environment.

Sustainability involves making use of the world's resources in ways that do not damage the environment.

True.

Sustainability involves using resources so that they remain available for the future.

If we continue current human activities, the consequences of global warming could be extremely serious for both humans and global biodiversity.

We can reduce the consequences of global warming by reducing carbon emissions and increasing the rate at which carbon is removed from the atmosphere.

A biofuel is a fuel made from recently living plant biomass, such as sugar cane, which can be burned to release energy.

True.

Biofuels are considered carbon neutral because the carbon they release was recently taken from the atmosphere by plants.

Burning biofuels instead of fossil fuels is one way to reduce carbon emissions.

The main existing mechanism for removing carbon from the atmosphere is photosynthesis, which is carried out by plants and trees.