IB Biology SL D3.2.14 Continuous Variation Questions

Interpret a continuous human-trait distribution and identify its modal range and many intermediate phenotypes in IB Biology SL D3.2.14.

Exam points

Read a continuous human-trait distribution and identify the modal range, recognizing that many intermediate phenotypes can occur.

[Maximum number: 1]

Both the genome and the environment of an organism affect its growth and development. Variation between individuals of a species can be continuous or discrete (discontinuous). Mitosis produces identical cells for growth and meiosis allows for variation.

The micrographs show onion and whitefish cells in mitosis.

Micrographs compare onion and whitefish cells. X points to a large onion cell with visible condensed material; the whitefish cell shows two separated dark chromosome groups.

The National Health and Nutrition Examination Survey in the USA measured heights of individuals aged 21-79. Height is an example of continuous variation.

Histogram of individual heights in centimetres, with a roughly bell-shaped distribution centred near 170 cm and few individuals at either extreme.

State the range of heights that is the mode.

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IB Biology SL D3.2.14 Continuous Variation Questions question 1