How many QCAA Biology questions cover Biodiversity and populations?

AusGrader has 87 QCAA Biology questions on Biodiversity and populations, all with instant AI grading and detailed marking feedback.

QCAA (QCE) Biology — Biodiversity and populations Questions & Answers | AusGrader

Q11

2020

QCAA

Paper 1

1 mark

Q11

1 mark

The Linnaean system originally used which type of evidence for classifying organisms?

A

physical features

B

common ancestry

C

molecular phylogeny

D

reproduction methods

Q9

2020

QCAA

Paper 1

1 mark

Q9

1 mark

The table provides population statistics for a species of tree kangaroo in northern Queensland.

Year	Births	Deaths	Immigration	Emigration	Final population
2016	253	175	153	131	1100
2017	290	167	182	140

Determine the population growth rate for tree kangaroos in 2017.

A

14.6%

B

15.0%

C

26.5%

D

86.9%

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

Q12

2021

QCAA

Paper 2

5 marks

Q12

An investigation compared mangrove species diversity for two areas of different size in the same catchment.
The table shows species population counts for each area.
Total species count

	Area 1	Area 2
Grey mangrove	37	7
Red mangrove	32	3
Yellow mangrove	25	88
SDI	0.67	?

Q12a

2 marks

Calculate Simpson's diversity index for Area 2. Show your working.

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

SDI = ____________________ (correct to two decimal places)

$SDI = 1 - (\frac{7(7-1)+3(3-1)+88(88-1)}{98(98-1)})$

= 0.19

Marking Criteria

Descriptor	Marks
Shows substitution correctly performed	1
Determines SDI = 0.19	1

Q12b

3 marks

Using your answer for Question 12a), compare the diversity of the two areas.

Area 2 has lower SDI than Area 1. While the communities' total populations are similar (94 to 98), Area 2 has a species that is dominant (Yellow mangroves) which causes the SDI in Area 2 to be much lower than Area 1.

Marking Criteria

Descriptor	Marks
States a relevant similarity	1
States a relevant difference	1
States the significance of the identified differences	1

QCAA Biology Biodiversity and populations

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