Adeline S2 Science term1 unit7

What is air mainly made up of?

A mixture of gases.

What gas makes up about 78% of air?

Nitrogen.

What is the percentage of carbon dioxide found in the air?

0.04%.

Name two noble gases found in air.

Argon and neon (or helium).

How do we test for the presence of oxygen?

It relights a glowing splint.

What happens to hydrogencarbonate indicator when carbon dioxide is present?

It turns from red to yellow.

How does lime water change when carbon dioxide is present?

It turns from colourless to milky.

What paper is used to test for water in the air?

Dry cobalt chloride paper.

What colour change shows the presence of water vapor when testing with dry cobalt chloride paper?

It turns from blue to pink.

What is a key property of oxygen that makes it useful for industry?

Oxygen supports burning.

What is used in a welding torch?

Oxygen mixed with a fuel gas

What essential process relies on oxygen for human survival?

Breathing (or essential for survival of humans).

Where is bottled oxygen used when breathing air is difficult?

Climbing at high altitudes.

What is a key property of carbon dioxide regarding fire?

Carbon dioxide does not support burning.

Carbon dioxide is used in some fire extinguishers because it is denser than what?

Air.

What happens when carbon dioxide is released from a fire extinguisher near a fire?

It cuts off the oxygen supply.

What is solid carbon dioxide commonly called?

Dry ice.

What is dry ice used for when keeping food items fresh?

To keep frozen food cold.

What visual effect is produced on stage using dry ice?

Dense fog.

What important property does nitrogen have that makes it useful for food packaging?

Nitrogen is unreactive.

Why is nitrogen used to replace air in food packets?

To prevent the food from reacting with oxygen.

What is the boiling point of liquid nitrogen?

-196 °C.

What is liquid nitrogen used for in commercial freezing systems?

To freeze foods rapidly.

Give an example of living material stored using liquid nitrogen.

Living cells or tissues (e.g. cord blood).

What process do plants use to make their own food?

Photosynthesis.

Where does photosynthesis mainly occur in plants?

In the leaves.

What structures inside green leaf cells contain the green pigment?

Chloroplasts.

What is the green pigment that absorbs light energy called?

Chlorophyll.

What energy source does chlorophyll absorb for photosynthesis?

Light energy.

What two reactants are changed into food and oxygen during photosynthesis?

Carbon dioxide and water.

What is the food substance produced during photosynthesis?

Glucose.

What is the new substance formed (product) in photosynthesis?

Oxygen and glucose.

In photosynthesis, light energy is converted into which type of energy in food?

Chemical energy.

What are the raw materials consumed in a chemical change like photosynthesis called?

Reactant.

What happens to some of the glucose produced immediately?

It is used by the plant to provide energy.

What substance is glucose converted into and stored in green leaf cells?

Starch.

What solution is used to test for starch?

Iodine solution.

What colour change shows the presence of starch during the iodine test?

It turns from brown to blue-black.

What is the purpose of boiling the leaf in water during the starch test?

To destroy the cell membranes.

Why is the leaf put into hot alcohol during the starch test?

To dissolve chlorophyll.

What is the process of putting plants in the dark for at least 24 hours called?

Destarching.

Why is destarching performed before photosynthesis experiments?

To ensure any starch detected is made during the experiments.

How is chemical energy transferred from plants to animals?

Through feeding (or a food chain).

What do we call plants in a food chain because they make their own food?

Producers.

What process releases energy stored in food gradually inside living cells?

Respiration.

What gas is usually needed during respiration to break down food?

Oxygen.

Other than carbon dioxide, what is the other main product usually produced during respiration?

water.

When plants are under light conditions, what is the net gas exchange for carbon dioxide?

A net uptake of carbon dioxide.

When plants are under light conditions, what is the net gas exchange for oxygen?

A net release of oxygen.

Under dark conditions, which gas is released by plants?

Carbon dioxide.

What are the pores on leaves called that allow gases to move in and out?

Stomata.

Name the tiny cup-shaped structures in the lungs where gas exchange occurs.

Air sacs.

What tiny blood vessels cover the surfaces of air sacs?

Capillaries.

What sheet of muscle below the lungs helps bring about breathing?

Diaphragm.

How does the percentage of oxygen change between inhaled and exhaled air?

Exhaled air contains less oxygen (21% to 16%).

What percentage of exhaled air is carbon dioxide?

4%.

What substance in cigarette smoke reduces the oxygen-carrying ability of blood?

Carbon monoxide.

What is the warming effect caused by gases like carbon dioxide trapping thermal energy in the atmosphere?

The greenhouse effect.