IB Biology Topic 4

Over time, the hull of a sunken ship may become colonized by a wide range of marine organisms. What term is used to describe all of the organisms living in and on a sunken ship?

• A community

• An ecological niche

• A population

• An ecosystem

Which organism would be classified as a saprotroph?

• A single-celled eukaryote that obtains its carbon compounds by photosynthesis and ingestion of other single-celled organisms

• A jellyfish that uses the stinging cells in its tentacles to paralyse its prey, which is passed to an internal gastric cavity through a single opening

• A fungus that feeds by secretion of digestive enzymes onto its food and absorption of digested material

• A dung beetle that feeds on the fecal material left behind by other animals

Which level(s) of ecological complexity involve(s) biotic factors but not abiotic factors?

• Community

• Ecosystem

• Population

How can a chi-squared test be used in ecological research?

• To test the effect of an abiotic factor on one plant species

• To test whether two species tend to live together

• To test whether one population of plants is taller than another

• To test whether one species is more tolerant to heavy metals than another

What is the ecological term for a group of different types of organisms that live together and interact with each other?

• Community

• Domain

• Ecosystem

• Population

Which organism can best be described as a saprotroph?

• A fungus that digests its food externally and absorbs the products of digestion

• A beetle that feeds by ingesting the dung of other animal species and digesting its food internally

• A single-celled eukaryote that is able to photosynthesize and consumes smaller organisms by endocytosis

• A giraffe that feeds by ingesting leaves from an acacia tree

Which is not essential in a viable mesocosm?

• Light source

• Autotroph

• Saprotroph

• Herbivore

The Australian pitcher plant (Cephalotus follicularis) is a green plant that traps and feeds on flies and other live insects. What is this plant’s mode of nutrition?

• Producer and saprotroph

• Autotroph and detritivore

• Autotroph and heterotroph

• Consumer and saprotroph

In 1789 Gilbert White, a naturalist, observed eight breeding pairs of swifts (Apus apus) in the English village of Selborne. On average, each pair of swifts produces two offspring per year. This would allow the population to rise to 1030 swifts over 200 years. A bird survey carried out in 1983 revealed only 12 breeding pairs in this village.

What could have prevented the numbers rising to 1030?

• The number of nesting sites remained the same.

• The food supply of the swifts remained constant.

• Predatory birds in the area were exterminated.

Limpets are molluscs with conical shells that cling tightly to rocks on seashores. In a study of two species of limpets found on rocks along the Oregon coast, 30 randomly placed quadrats were used to determine how often the two species occurred together. The table shows the data that were collected.

Which statistical method will determine whether these two species occur together by chance or by some kind of interaction?

• Chi-squared test

• t-test

• Standard deviation

• Means and ranges