Human Influences on the Environment: Answers

Name the environmental problem causes by sulfur dioxide. What effect does it have on the environment?

Sulfur dioxide in the atmosphere forms acid rain when it reacts with water vapour. This makes ponds and rivers more acidic, harming marine life. It also causes damage to limestone buildings and statues.

Why is carbon monoxide poisonous?

Carbon monoxide is poisonous because it binds to the haemoglobin inside red blood cells instead of oxygen. This reduces the amount of oxygen that our red blood cells can carry, so less oxygen is transported to our tissues for aerobic respiration.

Name the five greenhouse gases.

The greenhouse gases are carbon dioxide, water vapour, CFCs, methane and nitrous oxide.

Name a source of nitrous oxide.

Nitrous oxide is released from power stations, burning fossil fuels or from car exhausts.

List the consequences of global warming.

Global warming can result in the polar ice caps melting. This causes a rise in sea levels which can result in flooding and the destruction of habitats. It can also result in extreme weather events such as typhoons, hurricanes and draughts.

How can indicator species be used to determine pollution levels?

Indicator species are species which presence or absence in a habitat can tell us how polluted it is. For example, the stonefly nymph cannot tolerate even low levels of pollution so its presence in ponds and streams indicates that the water is not polluted.

Describe how eutrophication can result in death of marine life in ponds and rivers.

Eutrophication occurs when fertilisers from nearby farmland is washed into ponds and river by rainwater in a process called leaching. The fertilisers increase the growth of algae which grow so much that they completely cover the surface of the pond in an algal bloom. The algae block sunlight from reaching the bottom of the pond, which prevents plants living on the plant floor from photosynthesising. These plants die and are decomposed by bacteria which thrive and use up all of the oxygen available in the pond for respiration. This reduces the amount of oxygen available for other marine life, which prevents them from respiring properly and causes them to die.