IB DP Biology- D4.3 Climate change - IB Style Questions For SL Paper 2 - New Syllabus

(a)

An autotroph obtains energy from light or external chemical sources and uses this energy to make complex carbon compounds from simple or inorganic molecules.

(b)

Decomposers such as bacteria and fungi break down dead organic matter and faeces. During decomposition, nutrients and minerals are released and recycled back into the environment, making them available for uptake by other organisms.

(c)

Energy transfer between trophic levels is inefficient because some of the energy is lost as heat during respiration and metabolism, so only a fraction of the energy is transferred to the next trophic level.

The efficiency can also differ because the length of food chains and number of trophic levels vary. In addition, some animals can digest more of their food, such as cellulose, than others, meaning a greater proportion of the ingested energy can be absorbed.

Differences in activity and body size can also affect energy use. For example, animals that use more energy for maintaining body temperature have less energy available for transfer to the next trophic level.

(d)

Cattle farming can contribute to climate change because cattle produce methane, which is a greenhouse gas. Increasing cattle populations therefore increase the release of greenhouse gases into the atmosphere.

Increasing cattle farming can also lead to deforestation to provide land for grazing. This reduces the removal of carbon dioxide from the atmosphere by photosynthesis. Burning forests to clear land also releases carbon dioxide.

The increased concentrations of greenhouse gases such as methane and carbon dioxide enhance the greenhouse effect, causing global warming and contributing to changes in climate patterns.