SCSA Human Biology Science Inquiry Skills
5 sample questions with marking guides and sample answers · Avg. score: 64.9%
Students used quadrats to investigate biodiversity in a grassland community with scattered distribution of plant species. The students agreed on a counting criteria for each quadrat to
reduce the time taken to count the different species.
minimise statistical uncertainty.
ensure all strata were sampled.
minimise bias.
In 2009, the University of California discovered a mutated gene that has been shown to produce naturally short sleepers. The gene was found in a family who all normally went to bed around 11 pm and woke up naturally around 5 am. The mutated gene, known as DEC2, is believed to affect the circadian rhythm and results in people who don't need as much sleep as the average person.
If researchers wanted to further investigate the link between the DEC2 gene and sleep, they would need to set up an experimental study.
DEC2 is a gene mutation. How do gene and chromosomal mutations differ?
In the study, the mutation was found in several family members. What does this tell you about where the original mutation occurred? Justify your response.
Mutations can be caused in several ways. For each of the three ways stated below, describe how they may produce new mutations.
-
Mutagens:
-
DNA replication:
-
Cell division:
Propose a possible hypothesis for the study.
In the study, what would the control group consist of, and what purpose would it have?
A mutation, such as the DEC2 gene, could be favourable to the human population. Explain how a favourable gene like this could lead to changes in allele frequencies of a gene pool.
The effect of an invasive species on plant biodiversity was investigated by collecting this data from an ecosystem.
| Percentage cover (invasive species) | |||||
|---|---|---|---|---|---|
| 0–20% | >20–40% | >40–60% | >60–80% | >80–100% | |
| Species richness | 7 | 7 | 7 | 4 | 2 |
| Simpson’s diversity index | 0.83 | 0.77 | 0.55 | 0.49 | 0.30 |
Contrast species richness in areas of low invasive species cover (0–20%) with areas of high invasive species cover (>80–100%).
Draw a conclusion about the effect of the invasive species on plant biodiversity in this ecosystem. Justify your response.
Explain why having data on species richness and Simpson’s diversity index is more informative than a single measure for the purpose of this investigation. Refer to the table to support your response.
The table shows data from a transect study along a sand dune.
| Zone | ||||
|---|---|---|---|---|
| A | B | C | D | |
| Distance from sea (m) | 0–100 | >100–150 | >150–250 | >250–300 |
| Age of dune (years) | 0–50 | >50–100 | >100–125 | >125–150 |
| pH of soil | 8.4 | 7.4 | 6.9 | 6.0 |
| Organic matter in soil (%) | 1 | 2.5 | 5 | 30 |
| Number of grass species | 2 | 4 | 6 | 2 |
| Number of tree species | 0 | 1 | 3 | 8 |
Contrast species richness in zones A and D. Refer to data in your response.
Infer how organic matter affects the pH of soil. Justify your response.
Predict which zone would have the highest proportion of K-selected species. Explain your reasoning.
A computer simulation was used to observe genotypic changes in the gene pool of 20 randomly selected rabbits. The simulation was set with these parameters:
- each rabbit's coat colour was either black or white
- black alleles were dominant; white alleles were recessive
- the number of rabbits was constant in each generation and breeding was random throughout the population
- an environmental factor was chosen in the simulation to provide selection pressure.
The table shows the results of the simulation at the start and after 20 generations.
| Initial population genotypes | Population genotypes after 20 generations |
|---|---|
| BB BB BB BB BB BB | BB BB |
| Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb | Bb Bb Bb Bb Bb Bb Bb Bb |
| bb bb bb bb | bb bb bb bb bb bb bb bb bb bb |
Contrast the initial allele frequency with the allele frequency after 20 generations to draw a conclusion about the effect of the selection pressure on the rabbit population.