ScienceYear 9

Year 9 Science – Living Systems: Ecology 1

Practise explaining cause and effect in ecosystems, doing two-step energy pyramid calculations and drawing conclusions from investigation and population data. 20 questions. 25 minutes.

A long drought sharply reduces the growth of grass in a paddock where kangaroos graze and dingoes hunt. Which sequence of effects is most likely?

Less grass, then fewer kangaroos, then fewer dingoesFewer dingoes, then more kangaroos, then less grassFewer kangaroos, then less grass, then fewer dingoesLess grass, then more kangaroos, then more dingoes

A student keeps frog eggs in four identical containers of pond water at different temperatures and counts how many hatch. Which is the dependent variable?

Temperature (°C)	Tadpoles hatched out of 20 eggs
10	4
15	9
20	14
25	17

The temperature of the waterThe number of tadpoles that hatchedThe volume of water in each containerThe number of eggs in each container

Choose the word that completes each blank.

A disease spreading through wombats is a ₁ factor, while a fall in rainfall is classified as ₂.

Blank 1: abiotic · biotic · decomposer

Blank 2: an abiotic factor · a biotic factor · a producer

For several years a landholder removes all dead leaves and fallen branches from a bush plot. Plant growth in the plot slows. Which explanation is best?

Dead matter no longer supplies glucose that plants use as foodDecomposers no longer pass energy to the living plantsDead leaves no longer give the soil warmth for plant growthNutrients in the dead matter are no longer returned to the soil

Choose the word that completes each blank.

Bacteria in the soil break down a dead animal, so they act as ₁. The nutrients they release are taken up by ₂, which use them to grow and make glucose by ₃.

Blank 1: producers · primary consumers · decomposers

Blank 2: herbivores · fungi · plants

Blank 3: photosynthesis · respiration · digestion

Circle 2 words in the sentence below.

A disease kills all the grasshoppers. Click the two organisms whose numbers are most likely to fall because of a food shortage.

grass→grasshopper→lizard→hawk

In a woodland, rabbits eat grass, mice eat seeds, foxes eat both rabbits and mice, and owls eat mice. Disease removes all the rabbits. What is the most likely short-term effect?

Mice are unaffected, because mice and rabbits eat different foodFoxes die out quickly, so mice and owls both increaseFoxes eat more mice, so mouse numbers and then owl numbers fallOwls increase, because foxes now have fewer prey to compete with them for

Food chains rarely have more than four or five trophic levels. What is the best reason?

Top consumers are too large for the producers to feedDecomposers take most of the energy from the upper levelsEnergy is destroyed completely once it passes the third levelToo little energy is left after repeated losses as heat

Choose the word that completes each blank.

Top consumers have the least energy available because about ₁ of the energy is lost at each step, mostly as ₂.

Blank 1: 10% · 90% · 50%

Blank 2: heat · light · sound

10.

Choose the word that completes each blank.

One tree can feed thousands of insects, so a pyramid of numbers can look ₁. An energy pyramid is always ₂.

Blank 1: upright · upside down · flat

Blank 2: upside down · flat · upright

11.

A grassland has 20 000 kJ of energy in its producers. Assume 10% passes to each next level. How much energy reaches the tertiary consumers?

2000 kJ20 kJ200 kJ2 kJ

12.

Circle 2 words in the sentence below.

In this food chain, 10% of the energy passes to each next level. Click the two organisms that receive less than 1% of the energy held by the algae.

algae→tadpole→dragonfly nymph→fish→heron

13.

Choose the number that completes each blank.

Secondary consumers hold 150 kJ, which is 10% of the energy in the primary consumers. So the primary consumers hold ₁ kJ and the producers hold ₂ kJ.

Blank 1: 1500 · 15 · 15 000

Blank 2: 1500 · 15 000 · 150 000

14.

How much energy was lost as heat, waste and uneaten parts between the producers and the secondary consumers?

Level	Energy (kJ)
Producers	50 000
Primary consumers	6000
Secondary consumers	600

44 000 kJ5400 kJ49 400 kJ600 kJ

15.

A student counts snails in one quadrat at a sunny site and one quadrat at a shady site, and compares the numbers. Which change would most improve the reliability of the results?

Count in several quadrats at each site and calculate averagesCount snails at the shady site onlyUse a larger quadrat at the sunny siteCount on a different day at each site

16.

Circle 2 words in the sentence below.

A student compares seedling height in light and dark trays. Click the two numbers that show the variable that was not kept the same.

Light:20mLwater|Dark:50mLwater

17.

Choose the word that completes each blank.

When rabbit numbers crash, fox numbers usually ₁ after a delay because there is less ₂.

Blank 1: rise · stay the same · fall

Blank 2: food · space · sunlight

18.

Which conclusion is best supported by the data?

Year	Rabbits	Foxes
1	900	20
2	600	50
3	300	60
4	500	35
5	800	25

Fox numbers rose every year because rabbit numbers roseRabbits fell as foxes rose, then rabbits recovered as foxes fellFoxes ate every rabbit by year 3, so rabbits died outRabbits and foxes always change in the same direction

19.

Which conclusion is correct for 1990 to 2010?

European carp were introduced to a river system in 1990.

Year	Carp per hectare	Native fish per hectare
1990	5	90
2000	40	60
2010	120	20

Native fish fell by 110 per hectare while carp rose by 125 per hectareNative fish fell by 70 per hectare while carp rose by 120 per hectareNative fish fell by 20 per hectare while carp rose by 115 per hectareNative fish fell by 70 per hectare while carp rose by 115 per hectare

20.

The lesser bilby became extinct in the 1950s. Which set of pressures best explains its extinction?

Hunting by people and poisoning by cane toadsSpread of myxomatosis and competition from carpPredation by foxes and cats, and competition from rabbitsOvergrazing by native kangaroos and predation by thylacines

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Year 9 Science – Living Systems: Ecology 1