ScienceYear 10

Year 10 Science – Living Systems: Ecology 1

Practise evaluating explanations, energy budgets, food web predictions and population data, including management of Australian species. 20 questions. 25 minutes.

Circle 1 word in the sentence below.

A tick lives on a kangaroo and feeds on its blood. Click the organism that is harmed in this relationship.

tickkangarooblood

A pond is monitored over summer. Which pair lists only abiotic influences from the data?

Month	Water temperature (°C)	Dissolved oxygen (mg/L)	Tadpoles per net
Jan	22	8	40
Feb	29	5	22
Mar	31	4	15

Water temperature and tadpoles per netDissolved oxygen and tadpoles per netTadpoles per net and monthWater temperature and dissolved oxygen

Choose the word that completes each blank.

Competition between two bird species for nesting hollows is a ₁ interaction, while a bushfire that destroys the hollows is an ₂ influence.

Blank 1: biotic · abiotic · producer

Blank 2: decomposer · biotic · abiotic

A student says decomposers in a compost heap recycle the energy in dead leaves back to plants. Which response best evaluates this claim?

Correct: decomposers return both matter and energy to the soil for plants to reuse.Incorrect: decomposers return matter to the soil, but the energy leaves the system as heat.Incorrect: decomposers return neither matter nor energy, as both are lost when organisms die.Correct: decomposers return energy to the soil, while matter is lost from the ecosystem.

Choose the word that completes each blank.

Nitrogen in a dead animal is returned to the soil by ₁. Most of the energy stored in the animal's body is released as ₂.

Blank 1: producers · decomposers · herbivores

Blank 2: heat · light · new matter

Choose the word or phrase that completes each blank.

A food web diagram shows ₁, but it does not show ₂.

Blank 1: how much energy moves in each link · who feeds on whom · how many species are decomposers

Blank 2: which organisms are consumers · the direction of energy flow · how much energy each link carries

Circle 2 words in the sentence below.

Foxes eat rabbits and mice. Rabbits and mice eat grass. All the foxes are removed. Click the two organisms whose numbers are most likely to rise first.

GrassRabbitsMiceFoxes

Choose the word that completes each blank.

Foxes are introduced to an island where small birds nest on the ground and eat insects. In the short term, bird numbers ₁ and insect numbers ₂.

Blank 1: fall · rise · stay the same

Blank 2: fall · stay the same · rise

A student claims energy transfer is exactly 10% at every step. Which evaluation of this data is best?

Level	Energy (kJ)
Producers	50 000
Primary consumers	4 000
Secondary consumers	600

Exact: 4 000 and 600 are both close enough to 10% of the level below.Not exact: the transfers were 12.5% then 6.7%, so 10% is only a rough estimate.Not exact: the transfers were 8% then 15%, so 10% is only a rough estimate.Exact: 10% of 50 000 is 4 000 and 10% of 4 000 is 600.

10.

Choose the number that completes each blank.

Secondary consumers hold 1 200 kJ and tertiary consumers hold 90 kJ. The transfer is ₁%, so ₂ kJ is lost between these levels.

Blank 1: 13.3 · 7.5 · 75

Blank 2: 1290 · 90 · 1110

11.

A farm can grow wheat for people to eat or feed the same wheat to beef cattle. Which explains why eating the wheat directly makes more of the Sun's energy available to people?

Wheat is a producer, so it passes on all of the Sun's energy to the people who eat it.Cattle recycle the wheat's energy back into the soil, so none of it reaches people.Feeding cattle adds a trophic level, so more energy is lost as heat before reaching people.Beef holds no usable energy, because all the wheat's energy is lost as heat in the cattle.

12.

Food chains in most ecosystems have only four or five trophic levels. Which explanation is best?

Too little energy remains after repeated losses as heat to support more levels.Too much matter is recycled by decomposers to support more levels.Too many producers are eaten by consumers to support more levels.Too little sunlight reaches the top consumers to support more levels.

13.

Which conclusion about koala numbers is best supported by the data?

Site	Eucalypt cover (%)	Maximum summer temperature (°C)	Koalas per km²
A	60	41	3
B	58	30	14
C	20	41	1

Both heat and low cover are linked to fewer koalas, as A differs from B and C differs from A.Eucalypt cover alone explains the pattern, as the site with the least cover has the fewest koalas.Temperature alone explains the pattern, as both hot sites have fewer koalas than the cool site.Neither factor matters, as sites A and B have similar cover but different koala numbers.

14.

Students count brine shrimp hatching in three trials at the same salinity. Which is the best response to the result in trial 2?

Trial	Shrimp hatched
1	31
2	5
3	33

Delete trial 2 because it is lower than the other two trials.Include it in the mean and conclude that hatching varies naturally.Replace it with 31 so that the results look consistent.Check for a difference in conditions in trial 2 and repeat that trial.

15.

Which conclusion is best supported by the data?

Year	Feral cats per km²	Bettongs per km²	Annual rainfall (mm)
2005	2	40	480
2010	5	25	470
2015	9	10	490

Cats caused the bettong decline, as both changed over the same years.Rainfall caused the bettong decline, as rainfall varied between years.Rainfall is unlikely to be the main cause, as it stayed similar while bettongs fell.Cats had no effect on bettongs, as cat numbers were low in 2005.

16.

Circle 2 words in the sentence below.

Click the two words that overstate what this kind of data can show.

Quollnumbersfellaftertoadsarrived,sothisprovestoadsweretheonlycause.

17.

A report claims carp do not harm native fish. Which evaluation of this data is best?

Year	Carp per hectare	Native fish per hectare
2018	5	120
2019	8	135
2020	12	150

Supported, because native fish numbers rose in every year.Too short to judge, because other factors such as rainfall may have raised native fish.Not supported, because carp numbers rose in every year.Not supported, because carp and native fish rose by different amounts.

18.

A new fish that eats only snails is added to a lake. Which is the most likely short-term effect on the algae?

Lake food web: algae → snails → small fish → large fish. Algae → tadpoles → small fish.

Algae fall, because the new fish needs algae to survive.Algae fall, because small fish numbers drop.Algae rise, because fewer snails graze on them.Algae stay the same, because tadpoles eat exactly as much as snails did.

19.

Which conclusion about fox control is best supported by the data?

Island A (foxes baited):

Year	Foxes per km²	Small marsupials per km²
2010	4	3
2015	1	9
2020	0.5	20

Island B (no baiting):

Year	Foxes per km²	Small marsupials per km²
2010	4	3
2015	4	3
2020	4	2

Fox control is unnecessary, as the unbaited island fell only slightly.Fox control raised numbers, as the baited island rose while the unbaited island did not.Fox control was the only cause, as fox and marsupial numbers changed together.Habitat protection raised numbers, as marsupials increased after 2010.

20.

Which evidence would best show that fox control, rather than other changes, is responsible for a bilby recovery?

Bilby numbers rising at one site after control beganFox numbers falling at one site during a year of high rainfallMore public reports of bilby sightings after control beganBilby numbers at controlled and uncontrolled sites over the same years in similar conditions

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Year 10 Science – Living Systems: Ecology 1