📚 Chapter 1: Photosynthesis and the Carbon Cycle
Grade 8 Science Assessment
📝 Total Questions:
30
✅ Pass Mark:
70%
⏱️ Time:
45 minutes
1
What does 'photo' mean in the word photosynthesis?
Making
Light
Energy
Food
2
What are the reactants in photosynthesis?
Glucose and oxygen
Water and carbon dioxide
Sunlight and chlorophyll
Glucose and water
3
What is the green pigment that captures light energy in photosynthesis?
Chlorophyll
Chloroplast
Glucose
Cellulose
4
What percentage of air around us is oxygen?
10%
20%
50%
78%
5
Which layer of the leaf contains cells that do most of the photosynthesis?
Upper epidermis
Palisade layer
Spongy layer
Lower epidermis
6
What are the tiny holes in leaves called that allow gases to diffuse in and out?
Pores
Stomata
Chloroplasts
Veins
7
Which mineral is needed to make chlorophyll?
Nitrate
Magnesium
Calcium
Phosphate
8
What happens to a plant if it doesn't have enough magnesium?
It cannot grow well and leaves look yellow
It will produce too much oxygen
It will grow faster
Nothing changes
9
Why is nitrate important for plants?
To make chlorophyll
To make proteins for growth
To absorb sunlight
To produce oxygen
10
What is the word equation for photosynthesis?
glucose + oxygen → water + carbon dioxide
water + carbon dioxide → glucose + oxygen
water + oxygen → glucose + carbon dioxide
carbon dioxide + oxygen → water + glucose
11
In the carbon cycle, how do animals get carbon?
By breathing in carbon dioxide
By eating plants or other animals
By drinking water
By photosynthesis
12
How is carbon dioxide returned to the atmosphere?
Through photosynthesis only
Through respiration and combustion
Through eating only
It never returns to the atmosphere
13
What are fossil fuels formed from?
Dead organisms buried millions of years ago
Rocks and minerals
Current plants and animals
Water and carbon dioxide
14
What is combustion?
When organisms respire
When carbon in fossil fuels combines with oxygen to form carbon dioxide
When plants make food
When water evaporates
15
How long does it take for fossil fuels to form?
A few years
Hundreds of years
Millions of years
One year
16
What is coal formed from?
Marine organisms
Plants from huge swamps
Dinosaurs
Rocks
17
Where do decomposers get their carbon from in the carbon cycle?
From the air
From dead plants and animals
From sunlight
From water
18
What is the difference between a fossil and fossil fuels?
There is no difference
Fossils are remains turned to rock; fossil fuels don't look like organisms
Fossils are newer than fossil fuels
Fossil fuels are only found in water
19
Where in a plant cell does photosynthesis happen?
Nucleus
Chloroplasts
Cell wall
Vacuole
20
Do plants respire?
No, they only photosynthesize
Yes, they respire all the time
Only at night
Only in winter
21
What does a plant use glucose for?
Only for energy
To make carbohydrates and other nutrients
To produce oxygen
Nothing, it is released
22
Which part of the leaf transports water to the cells?
Stomata
Veins
Epidermis
Wax
23
Why are leaves thin?
To save energy
So sunlight can easily reach the cells
To make them stronger
To reduce water loss
24
Carbon dioxide diffuses into the leaf through which structure?
Veins
Stomata
Roots
Stem
25
What is the first reason why photosynthesis is important?
It produces water
It provides energy in the form of chemical energy in nutrients for most organisms
It removes all carbon dioxide
It makes soil
26
What is the second reason why photosynthesis is important?
It removes all the water
It provides oxygen for the Earth's atmosphere
It creates new animals
It stops rain
27
What do we call the system showing how carbon moves through organisms?
The carbon cycle
The water cycle
The oxygen cycle
The nitrogen cycle
28
Why couldn't animals have lived on Earth if photosynthesis had never begun?
There would be no water
There would be no oxygen to breathe
There would be too much light
There would be no carbon dioxide
29
Oil and natural gas were formed from:
Swamp plants
Tiny marine organisms
Dinosaurs
Rocks and minerals
30
When bacteria first began photosynthesis about 4.7 million years ago, what did this change?
The temperature
Oxygen began to collect in the Earth's atmosphere
The size of Earth
Nothing changed
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