ScienceYear 9

Year 9 Science – Living Systems: Body Systems 1

Practise explaining how body systems work together, using data, calculations and cause-and-effect reasoning about organs, plants and Australian species. 20 questions. 25 minutes.

An amoeba gets oxygen by diffusion across its surface, but a human cannot. Which explanation is best?

Its volume grows faster than its surface area, so diffusion cannot reach inner cellsIts cells are larger than an amoeba's, so each cell needs more oxygen than diffusion suppliesIts surface area grows faster than its volume, so oxygen arrives faster than cells can useIts body temperature is higher, which stops oxygen diffusing across the surface

Choose the word that completes each blank.

Heart muscle cells together form a ₁, while the heart, blood and blood vessels together form an ₂.

Blank 1: organ · tissue · organism

Blank 2: organ system · organ · organism

Choose the word that completes each blank.

Red blood cells have no ₁, which leaves more room for ₂ to carry oxygen.

Blank 1: cell membrane · cytoplasm · nucleus

Blank 2: haemoglobin · plasma · platelets

Choose the word that completes each blank.

Blood leaving the heart is at high pressure, so arteries have ₁ walls. Veins have ₂ to stop blood flowing backwards.

Blank 1: thin · thick, elastic · porous

Blank 2: capillaries · alveoli · valves

Circle 1 word in the sentence below.

Sugars made in the leaves of a plant are stored in its carrot-like root. Click the tissue that carried them there.

xylemphloemstomata

A lung made of millions of tiny alveoli exchanges gas faster than one large sac with the same total volume. Why?

The many small sacs hold more air than one large sac of the same volumeThe many small sacs use muscle in their walls to push air into the bloodThe many small sacs have a greater total surface area for oxygen to crossThe many small sacs have thicker walls that stop carbon dioxide leaking out

Choose the word that completes each blank.

Water evaporating from the stomata in leaves is called ₁. This pulls water up the plant through the ₂.

Blank 1: respiration · photosynthesis · transpiration

Blank 2: phloem · xylem · guard cells

In emphysema the alveoli are destroyed, and people often feel very tired. What is the best explanation?

Less glucose is absorbed, so cells release less energyLess oxygen enters the blood, so cells release less energyLess urea is filtered, so muscles release less energyLess carbon dioxide is made, so the heart beats more slowly

Choose the word that completes each blank.

In a bottle-and-balloon model, pulling the rubber sheet down lowers the pressure so air flows in. In real lungs the ₁ contracts to do this, and the model has no ₂ for gas exchange.

Blank 1: diaphragm · lung muscle · bronchus

Blank 2: windpipe · sealed container · blood supply

10.

At rest, a student breathes 15 times each minute and moves 0.5 L of air in each breath. How much air does the student breathe in 10 minutes?

7.5 L150 L750 L75 L

11.

Circle 2 words in the sentence below.

A patient's kidneys have failed. Click the two substances that will build up in the blood.

ureaexcess saltsoxygenhaemoglobin

12.

A person's kidneys stop working and they receive no treatment. Which sequence is most likely?

Less urea is made, so the bladder stays empty and the blood thickensUrea leaves through the lungs instead, so the person breathes fasterUrea is not filtered out, so it builds up in the blood and harms the bodyWater is not absorbed, so faeces become runny and the person dehydrates

13.

Choose the word that completes each blank.

A dialysis machine takes over the job of ₁ urea from the blood. A person with only one working kidney usually stays healthy because the other kidney ₂.

Blank 1: making · filtering · absorbing

Blank 2: compensates · stops filtering · makes urea

14.

A cube-shaped model cell has sides of 3 cm. What is its surface area to volume ratio?

Compare: a 1 cm cube has a ratio of 6 : 1.

6 : 12 : 19 : 118 : 1

15.

How much more blood does the heart pump each minute during exercise than at rest?

Rest: 70 beats per minute, 70 mL of blood per beat. Exercise: 120 beats per minute, 100 mL of blood per beat.

7 100 mL1 500 mL12 000 mL4 900 mL

16.

A student draws a plant cell 20 mm wide, viewed with a 10× eyepiece and a 40× objective lens. What is the actual width of the cell?

0.5 mm0.4 mm8 000 mm0.05 mm

17.

Three celery stalks stood in coloured dye for 2 hours. Which conclusion do the results best support?

Stalk A (leaves on, still air): dye rose 4 cm. Stalk B (leaves on, fan blowing): dye rose 7 cm. Stalk C (leaves removed, still air): dye rose 1 cm.

Dye moves up the phloem faster when air moves around the leavesLeaves slow the movement of water up the stemRoots pull the dye up, so the leaves make no differenceWater moves up the stem faster when more is lost from the leaves

18.

Circle 2 words in the sentence below.

Click the two causes of species decline that involve changes to habitat rather than introduced species.

feral catsland clearingfoxesaltered fire regimes

19.

What percentage of the 1980 bilby population was left in 2020?

Year	Bilbies counted in a reserve
1980	2 000
2000	1 000
2020	500

20%25%50%75%

20.

Why has Australia's geographical isolation contributed to its high rate of mammal extinction?

Native mammals bred too slowly in isolation, so hunting wiped them outIsolation kept native mammals from spreading, so each species stayed too weak to competeNative mammals evolved without foxes or cats, so they lacked defences against themIsolation made Australia colder, so many mammals could not survive later warming

Homeschooling Dojo

Study first

Year 9 Science – Living Systems: Body Systems 1