How many SCSA Biology questions cover Science Inquiry Skills?

AusGrader has 52 SCSA Biology questions on Science Inquiry Skills, all with instant AI grading and detailed marking feedback.

SCSA (WACE) Biology — Science Inquiry Skills Questions & Answers | AusGrader

Q24

2023

SCSA

1 mark

Q24

1 mark

Most vinegar flies have wild type (reddish-brown) eyes. However, some mutants have white eyes and cannot see. Biologists conducted a laboratory experiment to compare the fitness of flies with wild type and white eyes.

The dependent variable in the experiment is the

A

laboratory conditions.

B

eye colour of the flies.

C

vision of the flies.

D

fitness of the flies.

Q3

2023

SCSA

1 mark

Q3

1 mark

The purpose of a 'control' in an experiment is to

A

determine the reliability of the experiment.

B

provide a comparison for the experimental treatment.

C

reduce the sample sizes needed for the experiment to be valid.

D

minimise the number of variables to be tested.

Q21

2024

QCAA

Paper 1

7 marks

Q21

In 2014, a group of scientists surveyed a plant community and determined Simpson’s diversity index (SDI) to be 0.84. They returned to the same site in 2024 and collected this data.

Species	Number of individuals
A	133
B	96
C	256

Q21a

2 marks

Calculate SDI in 2024 using the formula $SDI = 1 - \left( \frac{\sum n(n-1)}{N(N-1)} \right)$ . Show your working.

$SDI = 1 - \left(\frac{(133 \times 132) + (96 \times 95) + (256 \times 255)}{485 \times 484}\right)$

$= 0.61$

Marking Criteria

Descriptor	Marks
determines SDI as 0.61	1
provides appropriate working	1

Q21b

2 marks

The scientists noted that species richness was the same in 2024 and 2014.
Infer how species evenness changed over the 10-year period. Justify your response.

Species evenness decreased over the 10-year period. SDI considers both species richness and evenness — the greater the species richness and evenness, the higher the SDI value. As species richness was the same in both years but SDI decreased from 0.84 to 0.61, it can be inferred that species evenness was lower in 2024 than in 2014.

Marking Criteria

Descriptor	Marks
infers that species evenness decreased over the 10-year period	1
justifies inference using SDI data	1

Q21c

3 marks

Describe how sampling could be used to collect data for this investigation.
Include at least two strategies to minimise bias.

Quadrats could be randomly placed throughout the forest, and the number and type of plants observed in each quadrat recorded. This data could then be pooled and used to estimate the total number of each plant species at the site. The researchers could ensure that at least 10% of the site is sampled (by considering number and size of quadrats) and use a random-number generator to decide where to place the quadrats.

Marking Criteria

Descriptor	Marks
describes an appropriate surveying technique	1
identifies one strategy to minimise bias	1
identifies a second strategy to minimise bias	1

Q4

2020

QCAA

Paper 2

6 marks

Q4

An ecologist investigated the species composition of mangrove trees in a natural mangrove forest and an adjacent 30-year-old planted mangrove forest.

Three 10 m-wide belt transects were sampled from inland to the sea for each of the forests, each covering 100 m on average and placed to cover various strata.

The species diversity of Forest A was determined using the Simpson’s Diversity Index (SDI):

$SDI = 1 - \left( \frac{\sum n(n-1)}{N(N-1)} \right)$

	Population count
Species	Forest A (natural)	Forest B (planted)
Grey mangrove	91	77
Red mangrove	23	14
River mangrove	11	8
Orange mangrove	3	0
Diversity	0.46	?

Q4a

2 marks

Use the SDI formula to calculate the diversity index for Forest B. Round your answer to two decimal places.

SDI
$= 1 - \frac{77(77-1) + 14(14-1) + 8(8-1)}{99(99-1)}$
$= 0.37$

Marking Criteria

Descriptor	Marks
Demonstrates correct substitution	1
States SDI = 0.37	1

Q4b

3 marks

Identify three reasons why the ecologist used a belt transect rather than line transects or randomly placed quadrats for collecting data to compare these two forests.

Belt transects are used for abundance and distribution of species. Random quadrats can be used for abundance, not distribution, and line transects can be used for distribution, not abundance.
Random sampling doesn’t take into account strata (different areas) and may not cover all areas of habitat equally, giving inaccurate measures of diversity and abundance.

Marking Criteria

Descriptor	Marks
States 3 reasons	3
States 2 reasons	2
States a reason	1
Does not satisfy any of the descriptors above	0

Q4c

1 mark

Identify one way in which the ecologist minimised bias in the sampling.

Descriptor	Marks
States a way to minimise bias	1

Q25

2023

QCAA

Paper 1

6 marks

Q25

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

Q25a

1 mark

Contrast species richness in areas of low invasive species cover (0–20%) with areas of high invasive species cover (>80–100%).

Species richness is higher in areas with low invasive species cover (seven different species compared to two).

Marking Criteria

Descriptor	Marks
Identifies species richness is higher in areas with low invasive species cover	1

Q25b

2 marks

Draw a conclusion about the effect of the invasive species on plant biodiversity in this ecosystem. Justify your response.

The presence of the invasive species has a negative effect on biodiversity. While the same number of species were observed in the area when invasive species cover was 0–60% (7, as indicated by species richness), the SDI decreased from 0.83 to 0.3 as percentage cover increased. This indicates that overall, biodiversity decreased as percentage cover increased.

Marking Criteria

Descriptor	Marks
Identifies a relevant trend in the data	1
Draws a valid conclusion about the effect of the invasive species	1

Q25c

3 marks

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.

Species richness indicates the number of species that can coexist in the area; however, it doesn’t account for the abundance of each species, so one or two species may be dominating. SDI considers the number of species and their relative abundance (evenness), but the number of species is not obvious from the index.
Having both values is more informative because it allows the researcher to identify the number of species in the area (7) and infer evenness from the SDI. For example, the same number of species was present for 0–60% coverage (7), but the evenness was not the same, as the SDI decreased as % coverage got higher.

Marking Criteria

Descriptor	Marks
Recognises species richness is the total number of species present	1
Recognises SDI considers species number and abundance/evenness	1
Uses data to explain why data on species richness and SDI is more informative than a single measure	1

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