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AP Biology 5.5 Environmental Effects on Phenotype

Practise AP Biology 5.5 questions by connecting environmental conditions with gene expression, phenotypic plasticity and measurable cellular changes.

Syllabus
Effective Fall 2025
Course
AP Biology

Exam points

  • explain how environmental conditions alter gene expression and phenotype
  • interpret temperature, soil and chemical cues as causes of phenotypic plasticity
  • design controlled comparisons that distinguish environmental from inherited effects
  • graph and interpret environmental-response data at organismal and cellular scales

Covered syllabus points

5.5.A—Explain how the same genotype can result in multiple phenotypes under different environmental conditions

5.5 Environmental Effects on Phenotype question 1

[Maximum number: 5]

Elevated levels of CO2\mathrm{CO}_{2} increase the rate of photosynthesis and growth in plants. Scientists studying the mechanisms involved in these increases examined a variety of species and found that when plants are exposed to elevated levels of CO2\mathrm{CO}_{2}, there is an increase in the number of chloroplasts per cell. To investigate whether the elevated levels of CO2\mathrm{CO}_{2} have a similar effect on the number of mitochondria in plant cells, the scientists then selected six of these species to quantify the number of mitochondria per cell when the plants were exposed to both normal and elevated levels of CO2\mathrm{CO}_{2} (Table 1).

TABLE 1. AVERAGE NUMBER OF MITOCHONDRIA IN PLANTS EXPOSED TO NORMAL AND ELEVATED LEVELS OF \(\mathrm{CO

TABLE 1. AVERAGE NUMBER OF MITOCHONDRIA IN PLANTS EXPOSED TO NORMAL AND ELEVATED LEVELS OF \(\mathrm{CO

Question (a)

(a)

Using the template in the space provided for your response, construct an appropriately labeled graph that represents the data in Table 1. Determine which species show(s) a difference in the number of mitochondria between normal and elevated levels of CO2\mathrm{CO}_{2}.

[ 4 ]

Question (b)

(b)

Based on the data in Table 1, describe the relationship between the level of CO2\mathrm{CO}_{2} and the average number of mitochondria per unit area of a cell.

[ 1 ]
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