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Question 1

What are the major components of air?

Answer 1

• Nitrogen – 78%
• Oxygen – 21%
• Noble gases (mainly argon) – 0.9%
• Water vapour and other gases – 0.07%
• Carbon dioxide – 0.03%

These components represent the approximate composition of Earth’s atmosphere.

Question 2

What is the test for oxygen?

Answer 2

It relights a glowing splint and causes it to burn more brightly.

This indicates the presence of oxygen in a sample.

Question 3

What is the test for carbon dioxide?

Answer 3

• Turns limewater from colourless to milky
• Turns hydrogencarbonate indicator from red to yellow

The color change indicates the presence of carbon dioxide.

Question 4

What color does hydrogencarbonate indicator turn at different concentrations of carbon dioxide

Answer 4

> 0.0%: Yellow
=0.04% Red
<0.04% Purple

This indicates a high concentration of carbon dioxide.

Question 5

What is the test for water and water vapour?

Answer 5

Turns dry cobalt chloride paper from blue to pink.

This indicates the presence of water.

Question 6

Is there a simple test for nitrogen and noble gases?

Answer 6

No, there are no simple tests because they are very unreactive.

This makes detection challenging.

Question 7

What are daily applications of oxygen?

Answer 7

• Help patients to breathe
• Oxygen + Hydrogen burns to cut metal

These applications highlight the importance of oxygen in medicine and industry.

Question 8

What are daily applications of carbon dioxide?

Answer 8

• Used in fire extinguishers to put out fire
• Solid carbon dioxide (dry ice) produces a fog effect on stage

This highlights its use in safety and entertainment.

Question 9

What are daily applications of nitrogen?

Answer 9

• Fills food packages to prevent spoilage
• Liquid nitrogen (-196ºC) used for storing living cells and tissue

This shows its role in food preservation and medical applications.

Question 10

What are daily applications of noble gases?

Answer 10

• Argon: Used to fill light bulbs
• Helium: Used to fill balloons and airships
• Neon: Used to fill advertising lights

These applications demonstrate their utility in various industries.

Question 11

What is the word equation for photosynthesis?

Answer 11

Carbon dioxide + Water → Glucose + Oxygen

This summarizes the process of photosynthesis.

Question 12

What is the chemical equation for photosynthesis?

Answer 12

6CO2 + 6H2O → C6H12O6 + 6O2

This shows the molecular transformation during photosynthesis.

Question 13

use of chlorophyll

Answer 13

to absorb light energy

Question 14

What are the raw materials for photosynthesis?

Answer 14

• Carbon dioxide obtained from the air
• Water absorbed from the soil

These materials are essential for the photosynthetic process.

Question 15

What is the test for the products of photosynthesis?

Answer 15

Use iodine solution to test for the presence of starch, which changes from brown to blue-black.

This indicates that starch has been produced during photosynthesis.

Question 16

What is destarching?

Answer 16

Placing the plant in the dark for at least 48 hours

This technique ensures that any detected starch is a result of photosynthesis.

Question 17

What are the necessary factors for photosynthesis?

Answer 17

• Chlorophyll
• Carbon dioxide
• Light
• Water

Each factor plays a crucial role in the photosynthesis process.

Question 18

What is the significance of photosynthesis to other living things?

Answer 18

• Helps maintain the balance of oxygen and carbon dioxide
• Provides food for living things

This illustrates the ecological importance of photosynthesis.

Question 19

What is the structure of a food chain?

Answer 19

Producer → Consumer → Consumer

This shows the flow of energy through an ecosystem.

Question 20

What is respiration?

Answer 20

A process to release energy from food by taking in oxygen to produce energy and carbon dioxide.

This occurs in cells and is essential for life.

Question 21

What is the word equation for respiration?

Answer 21

Glucose + Oxygen → Carbon dioxide + Water

This summarizes the process of respiration.

Question 22

What is the chemical equation for respiration?

Answer 22

C6H12O6 + 6O2 → 6CO2 + 6H2O

This illustrates the molecular transformation during respiration.

Question 23

What are the similarities between burning and respiration?

Answer 23

• Require oxygen
• Produce carbon dioxide

Both processes involve energy release.

Question 24

What are the differences between burning and respiration?

Answer 24

• Burning is quick, respiration is slow
• Burning occurs at high temperatures, respiration occurs at body temperature

This highlights the distinct characteristics of the two processes.

Question 25

What occurs during gas exchange in plants during the day?

Answer 25

Both photosynthesis and respiration take place, with a net uptake of carbon dioxide and net release of oxygen. ## Footnote This indicates the balance of gases during daylight.

Question 26

What occurs during gas exchange in plants at night?

Answer 26

Only respiration takes place, resulting in a net uptake of oxygen and net release of carbon dioxide. ## Footnote This shows the shift in gas exchange when photosynthesis cannot occur.

Question 27

What role do stomata play in plants?

Answer 27

Gas exchange is carried out through the tiny pores on the leaf epidermis called stomata. ## Footnote Guard cells control the opening and closing of the stoma.

Question 28

What are the differences between inhaled air and exhaled air?

Answer 28

* Inhaled air: More Oxygen (21%), Less Water vapour, Less Carbon dioxide (0.04%), Lower temperature * Exhaled air: Less Oxygen (16%), More Water vapour, More Carbon dioxide (4%), Higher temperature ## Footnote These differences highlight the changes in air composition during respiration.

Question 29

What is the pathway of air in the human breathing system?

Answer 29

Nasal cavity → Trachea → Bronchus → Bronchioles → Air sacs (gas exchange) ## Footnote This describes the route taken by air during inhalation.

Question 30

What are the effects of increasing carbon dioxide in the atmosphere?

Answer 30

* Traps heat from the Sun (greenhouse gases) * Disrupts the balance of carbon dioxide and oxygen * Increases average temperature → global warming ## Footnote These effects contribute to climate change.

Question 31

What are some harmful effects of climate change?

Answer 31

* Melting of ice in polar regions * Rising average sea levels → flooding in low-lying coastal areas * Loss of habitat for polar living things * More frequent heat waves, storms, and droughts * Food shortages due to unfavorable weather for crops ## Footnote These represent significant ecological and humanitarian challenges.

Question 32

use of destarching

Answer 32

ensures the plant does not contain any starch when the investigation begins. Any starch we detect later is formed during the investigation, indicating that photosynthesis has taken place

Question 33

process of testing for products of photosynthesis

Answer 33

- Put the leaf in boiling water: destroy plant cell - Put the leaf in hot alcohol: remove chlorophyll - Wash the leaf in hot water: remove alcohol and make the leaf soft - Add iodine solution to the leaf: test for the presence of starch in the leaf

Question 34

oxygen during breathing

Answer 34

from air sacs into blood capillaries, blood carries to the body cells for respiration

Question 35

how to test if chlorophyll is a necessary factor for photosynthesis

Answer 35

use variegated leaves

Question 36

Co2 during breathing

Answer 36

carried by the blood flowing to the lungs, passes from blood into air sacs