Climate Change (Edexcel A Level Biology (A) SNAB): Flashcards

False.

Climate is measured over decades, so a single day reflects weather, not climate change.

Changes in atmospheric gas concentrations.

Volcanic activity.

Records of atmospheric CO₂ and global temperatures.

Pollen grains in peat and tree rings (dendrochronology).

Air is trapped in bubbles as the ice forms.

Deeper ice is older, so the gas composition shows CO₂ levels over time.

Dendrochronology is the study of tree rings to measure the climate during each year of a tree's growth.

Trees grow faster in warm years, producing wider rings.

Ring width therefore records the climate of each year.

Each plant species has unique pollen, so the species present at each layer can be identified.

Different species indicate different climates, showing how climate changed over time.

Peat builds up in layers over time.

New layers form on top, so the deeper you dig, the older the peat.

Thermometer readings from many places worldwide over long periods.

These are combined to show average global temperature change over time.

Other factors can also affect climate.

But combined with knowledge of CO₂ as a greenhouse gas, it is strong evidence.

The study of tree rings to measure past climate is called dendrochronology.

True.

Since the industrial revolution, CO₂ has risen to its highest recorded level.

Light rings form during fast spring/summer growth.

Dark rings form during slow autumn growth; one of each is a year.

In waterlogged, acidic conditions.

Dead plant matter partly decomposes and is compacted over time.

A greenhouse gas is a gas that absorbs radiation re-emitted from Earth's surface, trapping heat in the atmosphere.

Radiation from the Sun is re-radiated from Earth's surface.

Greenhouse gases absorb this radiation, trapping heat in the atmosphere instead of it escaping to space.

Carbon dioxide and methane.

It keeps the Earth warm enough for life.

Without it, Earth would have extreme temperature fluctuations like its neighbouring planets.

Anthropogenic climate change is warming of the atmosphere caused by human activities.

The combustion of fossil fuels to power factories, transport and homes.

A carbon sink is a natural store of carbon, such as trees, soils, peat bogs or the oceans.

Any three of:

• Intensive farming of ruminant cattle

• Decomposition in landfill sites

• Extraction of fossil fuels

Warming of the poles melts permafrost.

This releases methane from natural stores, adding to warming.

Global warming is the rise in global temperatures from greenhouse gases.

Climate change is the longer-term change in climate measures (temperature, rainfall, wind) that results.

Warming of the atmosphere caused by human activity is described as anthropogenic climate change.

False.

The greenhouse effect is a natural process; human activity has enhanced it by adding greenhouse gases.

Extrapolation is using existing data to predict values beyond the range measured, such as future global temperatures.

By extrapolating from existing data.

This is used to produce models of how climate may change.

The Intergovernmental Panel on Climate Change — a group of climate scientists worldwide.

They extrapolate data to predict future temperature change under different scenarios.

Because future human activity is uncertain.

Each model is based on a different scenario for greenhouse gas emissions.

To plan measures such as flood defences.

To encourage changes such as reducing fossil fuel use and increasing renewables.

We don't know which emissions scenario will occur or how effective future technologies will be.

Global climate patterns are also very complex.

A tipping point is a threshold beyond which climate change suddenly accelerates, such as permafrost melting releasing methane.

It releases stored methane, a greenhouse gas.

This causes further warming, which melts more permafrost.

A volcanic eruption.

Ash could reflect radiation back into space and cool the Earth.

Using existing data to predict future temperatures beyond the measured range is called extrapolation.

False.

Models have limitations and uncertainties, so they give predictions rather than exact certainty.

Humans immediately reducing fossil fuel use.

Doing nothing could see warming exceed 4 °C.

More infrared radiation is absorbed.

The atmosphere becomes warmer.

Longer, hotter heatwaves and more violent storms.

Changes to rainfall patterns — heavier in some places, drier in others.

Warmer air can hold more moisture.

This can bring heavier rainfall to some areas and reduced rainfall to others.

They move towards the poles or to higher altitudes to find cooler conditions.

Moving species may out-compete or fail to compete with residents.

Species that cannot move fast enough may become extinct.

Plants flowering earlier in the year.

Animals producing young earlier, and bird migration losing synchronisation with food supplies.

Warmer water expands.

Polar ice and glaciers are melting, adding water to the oceans.

Glaciers store fresh water.

Their loss can affect the water supplies of many people and surrounding wildlife.

As climate warms, many species shift their distribution towards the poles or to higher altitudes.

True.

If the Gulf Stream changed direction, parts of the UK's climate could actually cool.

Earlier plant growth shifts invertebrate life cycles.

Migrating birds may then arrive to find their usual food is no longer available.

Changing rainfall patterns may make the seasonal rains less frequent or absent.

These species may then be unable to survive and could migrate or go extinct.

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

Molecules have less kinetic energy and move slowly.

This gives fewer successful collisions and less enzyme-substrate complex formation.

Molecules gain kinetic energy and collide more often and with more energy.

This increases the frequency of enzyme-substrate complex formation.

It begins to denature.

Increased vibration breaks hydrogen and ionic bonds, changing the tertiary structure and active site shape.

The active site changes shape.

It is no longer complementary to the substrate, so no enzyme-substrate complex can form.

At high temperatures plants carry out more photorespiration, which uses rubisco.

This slows photosynthesis, reducing growth and yield.

In species where the sex of young is temperature-determined (e.g. alligators).

Rising temperatures can skew the sex ratio.

By the volume of oxygen produced over time.

Catalase breaks down hydrogen peroxide into water and oxygen.

To keep the pH constant.

This ensures only temperature affects the rate.

Q₁₀ is the factor by which the rate of reaction increases when the temperature is raised by 10 °C.

Q₁₀ = rate at higher temp ÷ rate at lower temp

= 6.8 ÷ 3.5 = 1.94 (close to 2, so the rate almost doubles)

False.

Denaturation is permanent — the active site is irreversibly damaged.

To eliminate other factors that could affect development.

Examples include light intensity and food availability.

Seedling growth rate.

Rate of hatching in brine shrimp.

average growth rate = average change in height ÷ days of incubation.

Any three of:

• Soil moisture

• Soil pH

• Light intensity (and same plant variety/age)

The high temperature causes cellular enzymes to denature.

This slows the reactions needed for growth.

hatching rate = number of hatched eggs ÷ hours in the water bath.

Any two of:

• Age of the shrimp eggs

• Water pH and volume

• Dissolved oxygen concentration

Return hatched shrimp to a suitable environment afterwards.

Handle them gently and quickly, and avoid dangerously high temperatures.

So the change in height can be calculated.

This gives a fair measure of growth over the incubation period.

Both seedling growth rate and shrimp hatching rate increase with temperature up to about 25 °C, then decrease.

False.

They increase up to an optimum, then decrease as enzymes denature.

They show how rising temperatures affect the development of organisms.

This helps predict how global warming may affect living things.

That increasing greenhouse gases cause global warming.

And that human activities are the direct cause of the rising gas concentrations.

A scientific consensus is a position that the great majority of the scientific community agrees on, based on the evidence.

The source may have a financial or political interest in the outcome.

This could bias the claims they make.

They have a financial interest in fossil fuels.

This could bias them towards downplaying human causes.

It shows the finding is reliable and not a one-off.

Multiple independent studies build stronger, more trustworthy evidence.

Climate is highly complex and any year is affected by many factors.

It is better to look at that event's place in a long-term trend.

There is a strong overall upward trend.

Short-term dips do not address all of the long-term evidence.

Whether it addresses all the evidence, is reliable, comes from several studies, and is statistically significant.

A source with a financial or political interest in a study's outcome is likely to be biased.

False.

There is a strong consensus, but a few individuals still dispute the causal link.

They have an emotional stake in the outcome.

Strong belief that humans cause climate change could bias their interpretation.

Climate change is not linear.

Beyond a tipping point, changes could happen much faster, making exact predictions hard.

The carbon cycle is the set of processes by which carbon is transferred between living organisms, the atmosphere, oceans and stores.

By producers during photosynthesis.

It can also dissolve into the oceans.

By respiration of plants, animals and decomposers.

By combustion of fossil fuels and biomass.

By feeding — one organism consuming and digesting another.

They break down dead organisms.

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

From dead organisms that are not fully decomposed.

Over millions of years their carbon is stored as fossil fuels.

It shows where carbon enters the atmosphere (to reduce) and where it is removed (to increase).

For example, cutting fossil fuel combustion and planting trees.

Marine plants use it in photosynthesis.

Other organisms use it to build calcium carbonate shells and exoskeletons.

Carbon dioxide is removed from the atmosphere by producers during photosynthesis.

True.

Damaging carbon sinks such as peat and soils releases stored carbon back into the atmosphere.

A carbon sink is a store that holds carbon, such as forests, soils, peat bogs, fossil fuels and the oceans.

Photosynthesis.

Reducing carbon emissions.

Increasing the removal of carbon from the atmosphere.

A biofuel is a fuel made from recently living plant biomass, such as sugar cane, that can be burned in place of fossil fuels.

They only release carbon that was recently removed from the atmosphere by the growing plants.

Unlike fossil fuels, they do not release carbon stored for millions of years.

Land used for biofuels could grow food instead, and clearing land (e.g. rainforest) harms biodiversity.

Cutting mature trees also reduces carbon removal by photosynthesis.

They release no carbon dioxide when generating electricity.

The technology is advancing and becoming cheaper and more efficient.

Solar depends on hours of sunshine.

Geothermal can only be used where there is volcanic activity near the surface.

Technology to remove and store vast quantities of carbon does not yet exist.

Photosynthesis is the main existing removal method.

By stopping deforestation.

By reforestation — planting trees that store carbon as they grow.

Reforestation is the planting of trees to restore forests, increasing the removal of carbon dioxide by photosynthesis.

Allowing trees to grow to maturity stores large amounts of carbon in their biomass.

False.

Biofuels do release carbon dioxide when burned — but only carbon recently taken from the atmosphere.

So many daily activities depend on it — transport, electricity generation and food production all rely on fossil fuels.