Plant Cells, Fibres and Sustainability: Practice Questions

A scientist calculated the heterozygosity index for a population of endangered orchids. If there are 12 heterozygotes in a population of 80 individuals, what is the heterozygosity index?

A student used the index of diversity formula \( D = \frac{N(N-1)}{\sum n(n-1)} \) to compare two different meadows.

In Meadow 1, there are two species: Species X (\( 40 \) individuals) and Species Y (\( 10 \) individuals).
In Meadow 2, there are two species: Species X (\( 25 \) individuals) and Species Y (\( 25 \) individuals).

Which of the following statements correctly evaluates the biodiversity of these two meadows?

A plant is grown in a hydroponic solution that is deficient in calcium ions. Which of the following structural consequences is most likely to occur in this plant?

Contemporary drug testing involves several distinct phases. Which of the following correctly describes the primary purpose and group size of Phase I clinical trials?

A population of a rare orchid species consists of 200 individuals. Genetic analysis reveals that 40 of these individuals are heterozygous for a particular enzyme locus. What is the heterozygosity index for this population?

A student carries out Core Practical 8 to determine the tensile strength of plant fibers. They use extracted fibers from the stems of two different species of plants, A and B. Both sets of fibers are standardized to a length of 20 cm.

(a) Describe a procedure the student should use to measure the tensile strength of these fibers and ensure the results are reliable. (3)

(b) State two variables, other than the length of the fibers, that must be controlled to allow for a valid comparison between species A and B. (2)

(c) Explain how the arrangement of cellulose microfibrils and the presence of lignin in the cell walls of sclerenchyma fibers contribute to their high tensile strength. (2)