🌱 Chapter 4: Maintaining Life
Grade 8 Science Assessment
📝 Total Questions:
30
✅ Pass Mark:
70%
⏱️ Time:
45 minutes
1
What percentage of a plant is made up of water?
About 50%
Mostly water (almost all of the time)
About 10%
No water at all
2
Where do plants absorb water from?
The air
The soil through their roots
The leaves
The stem
3
What are root hairs?
Special cells that grow out of the surface of roots
Actual hairs like on humans
The main root of the plant
Leaves that fell off
4
Why do root hair cells provide a really big surface?
To make the plant look nice
So water and mineral ions can be absorbed into the plant
To protect the root
To store food
5
Which minerals do plants need?
Gold and silver
Magnesium and nitrate
Carbon and hydrogen only
Iron and copper
6
In what form are minerals dissolved in water?
As solid particles
As ions
As gases
They don't dissolve
7
What are xylem vessels?
Living cells that transport food
Long, tube-like dead cells that transport water
Cells that make food
Cells in the leaves only
8
Why are xylem vessels described as dead cells?
They are brown in color
Their contents (cytoplasm, nucleus) have disappeared, leaving empty space inside
They don't work anymore
They are outside the plant
9
Where are xylem vessels located in a root (cross-section)?
On the outside
In the centre
Only in the leaves
They are not in roots
10
Where are xylem vessels located in a stem (cross-section)?
In a ring pattern
In the centre only
Randomly scattered
They are not in stems
11
What is transpiration?
The process of making food
The loss of water vapour from the surface of leaves
The absorption of water by roots
The movement of minerals
12
Through which structures does water vapour diffuse out of leaves?
Veins
Stomata
Roots
Stems
13
Where does most transpiration happen from?
The top of the leaf
The underside of the leaf
The stem
The roots
14
What happens to water when it arrives at a leaf?
It stays in the xylem vessels
It moves into the leaf cells and most evaporates
It returns to the roots
It becomes solid
15
What is the first reason why plants need water?
To make them green
For support - it helps them stand upright
To produce oxygen only
To attract insects
16
What happens when a plant doesn't have enough water?
It grows faster
The plant wilts (collapses)
It changes color to blue
Nothing happens
17
What is the second reason why plants need water?
To make noise
For transport - it carries dissolved mineral salts
To produce flowers only
To protect from animals
18
What is the third reason why plants need water?
For decoration
For cooling - when water evaporates it takes heat away
To make seeds only
To change seasons
19
What is the fourth reason why plants need water?
For photosynthesis - water is one of the reactants
To make the plant heavy
To attract pollinators
To produce carbon dioxide
20
What is soil made up of?
Only water
Tiny particles of rock of different sizes with spaces filled with air and water
Only air
Only sand
21
How does water move into the root hair cell from the soil?
It is pumped in
It passes through the cell wall and cell membrane
Through special tubes
It doesn't move in
22
After water enters the root hair cell, where does it go?
It stays in the root hair cell
It moves towards the inside and goes into the xylem vessels
It goes back to the soil
It evaporates immediately
23
What makes up the wood in a tree trunk?
Root hair cells
Xylem vessels
Leaf cells
Stomata
24
What is the diameter of a xylem vessel?
About 1 cm
About 0.05 mm (very tiny)
About 10 cm
About 1 meter
25
How do desert plants adapt to reduce water loss through transpiration?
They have very large leaves
They reduce the amount of water lost (e.g., small leaves, thick waxy coating)
They stop photosynthesis
They don't need water
26
Where do cells that have chloroplasts use water for photosynthesis?
In the roots only
In the leaves (but they don't need very much water for this)
In the stem only
In the soil
27
Do most of the water molecules that enter a leaf stay in the cells?
Yes, they all stay
No, most of the water does not stay in the cell
Half stay, half leave
They turn into oxygen
28
What happens to liquid water in the leaf cell?
It freezes
It soaks into the cell wall and then changes to water vapour (evaporates)
It stays liquid forever
It turns into sugar
29
How does water vapour diffuse into the air spaces between cells?
Through pumps
It diffuses naturally from the cells into air spaces and out through stomata
It doesn't diffuse
Through the roots
30
Why do plant cells have a lot of water especially inside their vacuoles?
To make them colorful
When all cells in a plant are full of water, they press on one another and make the whole plant firm and well supported
To store nutrients only
To produce energy
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