NCEA Level 2 Biology (90461) 2011 — page 1 of 1
Assessment Schedule – 2011
Biology: Describe concepts and processes relating to ecology (90461)
Assessment Criteria
Achievement / Achievement with Merit / Achievement with ExcellenceDescribe biological concepts and processes relating to ecology requires the candidate to recognise, name, draw, give characteristics of or an account of biological concepts and processes relating to ecology. / Explain biological concepts and processes relating to ecology requires the candidate to provide a reason as to how or why something occurs with regards to biological concepts and processes relating to ecology. / Discuss biological concepts and processes relating to ecology requires the candidate to show understanding by linking biological ideas. It involves justifying, relating, evaluating, comparing and contrasting, and analyzing biological concepts and processes relating to ecology.
Evidence Statement
Question / Expected coverage / Achievement / Merit / Excellence /ONE / Describes both zonation and stratification, and provides an example of each.
Explains how the patterns occur and the abiotic factors that are involved in creating these patterns.
Compares and contrasts the two patterns to identify the similarities and differences in their nature and occurrence and gives reasons for these. / Describes BOTH processes (and gives at least 1 example)
• Zonation is the division of an ecosystem into distinct zones / bands / regions / in horizontal layering due to an environmental gradient (abiotic conditions).
Example: rocky shore.
• Stratification is the division of an ecosystem into distinct zones that experience similar abiotic conditions in a vertical orientation.
Example: tropical rain forest. / Provides ONE statement with an example.
• The pattern of zonation is due to different tolerance of species to one or more abiotic factors (may say environmental gradient). These should be appropriate to the habitat.
Eg, exposure to air, salinity, temperature etc.
• The vertical stratification that occurs within forests results from the varying degrees of key abiotic factors that the different strata are subject to. (light, temperature, humidity, wind etc.),.
Eg. the taller the plant and the more foliage it produces, the more light it can intercept. / Compares and contrasts the nature of BOTH patterns with examples.
Links the TWO patterns (so there must be an explanation of both), clearly discussing the key similarities and differences – vertical vs horizontal as being the way in which distinct sections of the patterns are differentiated, but that abiotic factors are the key driver of the pattern formation. The abiotic factors in stratification are themselves influenced by the nature of the plants.
Question / Expected coverage / Achievement / Merit / Excellence
TWO
(a) / The three terms are described, and an example of each provided. / Describes at least THREE statements.
In (a) describes:
• Producer:
A photosynthetic green plant or chemosynthetic bacterium that is the first trophic level in a food chain; an autotrophic organism; eg phytoplankton
Primary consumer:
An animal that eats green plants (producers) in a food chain; a herbivore, eg zooplankton
• Carnivore:
An animal that feeds on other animals. eg shrimp, flounder, squid, fur-seal, killer whale
In (b)
• Describes the loss of energy from one trophic level to the next (no explanation).
In (c)
• Describes a nutrient cycle, eg nutrients move from the physical environment into living organisms, and subsequently are recycled back to the physical environment.
Provides at least ONE example (details of minerals involved are NOT required), eg carbon cycle. / Explains at least THREE statements from Merit.
In (b) provides explanation for the limited nature of most food chains.
• There is an energy loss of about 90% from one trophic level to the next due to respiration / metabolism, therefore a food chain with only a few trophic levels results in more energy being available to the final trophic level.
• Most other ecosystems have a lower growth / production rate and cannot provide sufficient transferable energy for such a long food chain.
In (c) Provides at least one example to:
• Explain the importance of nutrient cycles to ecosystems E.g. Without them the nutrients would be unavailable to living organisms and ecosystems would be unsustainable.
• Explain nutrient cycle, eg that nutrients move from the physical environment into living organisms, and subsequently are recycled back to the physical environment.
• Explain one difference, eg renewable vs non-renewable. / Justifies the importance of nutrient cycles (Bullet point 1) AND contrasts the two processes with examples
• Without nutrient cycles, living organisms could not access the nutrients and ecosystems would be unsustainable.
OR the regulation of nutrients by a cycle prevents an imbalance and perhaps the collapse of the ecosystem.
AND
The fact that nutrient cycles are the movement of substances in a cyclical process that involves constant re-use and recycling.
OR
• The source of nutrients in any cycle is finite,
AND
• This contrasts to the energy flow in food-chains and webs, which is uni-directional.
OR
• Food chains and food webs rely on a source of energy which is constantly renewed (ultimately by the sun).
(b) / Explanation of why food chains are normally limited to a few steps, because of the limited amount of energy that is passed from one level to the next.
(c) / Description of what a nutrient cycle is.
Explains the importance of nutrient cycles to an ecosystem.
Discusses how they differ from the energy flow of food chains / webs.
Question / Expected Coverage / Achievement / Merit / Excellence
THREE / Describes inter- and intra-specific competition accurately.
Explains what adaptations are and how they allow species to avoid competition.
Discusses the impact of environmental change on biodiversity and why it is likely to have a greater impact than competition from introduced species. / Describes at least THREE statements from:
• Defines inter-specific competition as competition between members of a different species.
• Defines intra-specific competition as competition between members of the same species.
• Describes an adaptation as the evolutionary process whereby a population becomes better suited to its habitat (accept other reasonable descriptions).
• Names and describes at least two types of adaptation from: structural (physical); physiological; behavioural.
• Defines biodiversity as the diversity (number and variety of species) of plant and animal life within a region.
• Environmental change tends to reduce biodiversity. / Explains any TWO statements from:
Explains that:
• Inter-specific competition is likely to increase when new species are introduced to an area but that the native bees seem to be competing well.
• Adaptations of the native bees in terms of their structure, physiology and behaviour make them better suited to exploit the native vegetation of NZ compared to the introduced species which are more likely to be successful on introduced plants from their own parts of the world.
• Environmental change is mostly caused by human activity, which over the last millennium has been significant in terms of loss of habitat and resources, which has significantly reduced the biodiversity in many areas. / Provides TWO (linked) statements.
Discusses the relative impacts of environmental change and competition linking explanations of both to a reasoned conclusion.
• The reduction in biodiversity brought about by environmental change is likely to have reduced available food and habitat sources for the native bees, which in turn may lead to local extinction or reduction in population size.
• The competition from the introduced species is less direct as many of these species are better adapted to live and feed on plant species that have also been introduced as part of the settlement of humans in NZ. The native bees can out-compete the introduced species as they are better adapted to the native environment.
Judgement Statement