Scientific Enquiry
What is a variable in a scientific investigation?
Anything that can be changed or measured in an experiment
Which tool is used to measure temperature?
Thermometer.
What does the M in MRS GREN stand for?
→ Movement.
What is the basic unit of life?
The cell.
Write the word equation for photosynthesis
Carbon dioxide + water → glucose + oxygen (in presence of light and chlorophyll)
In a fair test, which type of variable do we change on purpose?
The independent variable
Which piece of equipment should you use to measure the mass of a solid?
A balance
Give two examples of how plants show movement
Moving or growing toward light and roots growing downward
Name two structures found in plant cells but not animal cells.
Cell wall and chloroplasts
Why is chlorophyll important for photosynthesis?
It absorbs light energy needed to make food.
What is meant by the term reliable results?
Results that are consistent when the experiment is repeated.
You’re asked to measure 25 cm³ of liquid accurately — which is better: a 100 cm³ beaker or a 25 cm³ measuring cylinder? Explain.
The 25 cm³ measuring cylinder, because it gives more accurate and precise measurements
Why is excretion important for living organisms?
It removes harmful waste products like carbon dioxide and urea
What is the function of the mitochondria?
release energy through respiration.
Why do plants usually have broad, flat leaves?
To increase the surface area for absorbing light
Why should you repeat an experiment several times before drawing a conclusion?
To identify anomalies and improve accuracy and reliability.(to make a fair test)
During an experiment, a student spills a small amount of acid on the lab bench.
What’s the correct immediate action they should take?
Inform the teacher right away and neutralize the spill carefully
How is respiration different from breathing?
Respiration is a chemical process that releases energy; breathing is the physical movement of air in and out of the lungs(only gas exchange)
Describe the difference between cytoplasm and nucleus in terms of function
Cytoplasm is where chemical reactions happen; the nucleus controls cell activities
A plant is kept in the dark for 3 days and then tested for starch using iodine. Predict the result and explain why
No blue-black color appears because no photosynthesis occurred, so no starch was made.
A student measures how light affects plant growth but forgets to control water. Which part of the enquiry was not valid, and why?
It’s not a valid test because a control variable (water) wasn’t kept constant.
When heating a test tube, why should the open end of the tube be pointed away from people, even if the substance seems harmless?
heating can cause the liquid to boil suddenly and splash or release hot vapour, which could injure someone. Pointing it away prevents accidents.
Some seeds remain inactive for years and then start to grow. Which characteristic do they show when they start growing again?
Growth and also sensitivity to environmental change
When observing onion cells under a microscope, iodine is added. Why?
It stains the cell to make structures like the nucleus more visible.
A green plant is placed in a sealed transparent jar with a burning candle. After a few hours, the candle goes out. The next day, under sunlight, the same candle can burn again when relit inside the jar.
Explain scientifically what happened inside the jar
the candle initially used up oxygen and produced carbon dioxide, causing the flame to go out. During the next day, the plant used light energy to carry out photosynthesis, converting carbon dioxide and water into oxygen and glucose. The oxygen produced allowed the candle to burn again