Practise ecology and environment questions on sampling populations, biodiversity, food chains, biomass pyramids, energy transfer and carbon cycling.
The diagram shows part of a woodland food web.
Which organism is a primary consumer in this food web?
aphid
blackbird
fox
oak tree
Which of these describes the woodland community?
all the abiotic and biotic factors in the area
all the blackbirds in the area
all the different species and the habitat
all the different species in the area
This is one food chain from the food web.
A student counted 20 mice living around 4 oak trees. There were also 2 foxes in the area.
Draw a labelled pyramid of numbers for this food chain on the grid.
Your pyramid should be drawn to scale.
Photosynthesis results in 25000 kJ of energy being transferred to the biomass of the oak trees each year.
Only 8\% of this energy is transferred to the biomass of the 20 mice each year.
Calculate the mean amount of energy transferred to the biomass of one mouse each year.
mean amount of energy = kJ
Explain why only 8% of the energy stored in the biomass of the oak trees is used by the mice for growth.
Read the passage below. Use the information in the passage and your own knowledge to answer the questions that follow.
Plants to the rescue
Since the early 20th century, the concentration of carbon dioxide in the atmosphere has increased rapidly. This has further increased in recent years due to more cars and the increased demand for electricity for homes and industry.
Scientists have found that plants play a critical part in removing this excess carbon dioxide from the atmosphere. Using computer models, the scientists concluded that photosynthesis has increased by 30 per cent.
The scientists measured carbonyl sulfide found in ice cores and air samples. In addition to carbon dioxide, plants take in carbonyl sulfide gas during their natural carbon cycle, and this is frequently used as a measure of photosynthesis on a global scale. Terrestrial plants are removing about 29 per cent of carbon dioxide emissions that would otherwise contribute to an increase in the atmospheric carbon dioxide concentration.
A carbon sink is an ecosystem, such as a forest, that absorbs more carbon dioxide than it releases. The size of the carbon sink depends on the rate of photosynthesis but also on the levels of deforestation and respiration. The model the scientists used showed that the role of photosynthesis in producing a carbon sink in land plants is larger than estimated in most other models.
Other scientists are less confident about using carbonyl sulfide as a measure of photosynthesis. Plant absorption of carbonyl sulfide can vary depending upon the amount of light the plants receive. Therefore, the measure of global photosynthesis could be overestimated.
Regardless of the rate at which photosynthesis has increased, scientists agree that excess carbon dioxide is boosting the growth of plants. Trees are becoming leafier, and there is more wood. The wood is where most of the carbon is stored in the plant.
In experimental research, scientists exposed plants to double the normal concentration of carbon dioxide found in the atmosphere. Under these increased carbon dioxide conditions, the composition of the leaf tissues changed. This made the leaves tougher for herbivores to eat and made it harder for insect larvae to grow.
Scientists have also observed that when plants are exposed to increasing levels of carbon dioxide, the size of the stomatal pores on a leaf increases.
Explain why more cars would result in an increase in atmospheric carbon dioxide. (Lines 1-3)
Explain how increased carbon dioxide can cause climate change.
Explain why the carbon sink depends upon respiration and deforestation as well as photosynthesis. (Lines 13 to 15)
Using the recommended amount of fertiliser on a crop increases crop yield. Some farmers think that adding extra fertiliser will give an even greater crop yield.
Some farmers apply more nitrogen fertiliser and more water to their fields than are needed.
Explain the biological consequences of applying more nitrogen fertiliser and more water than needed.
The atmosphere can be polluted by gases such as carbon monoxide released from industry.
Describe the effects of carbon monoxide on the human body.
Which of these is not a greenhouse gas?
carbon dioxide
methane
nitrogen
nitrous oxide