Lesson: Respiration in organisms

# Question: 1

What are the two types of respiration in living organisms?

## Solution:

Aerobic and anaerobic respiration

# Question: 2

What are the end products of aerobic and anaerobic respiration?

## Solution:

End products of:

Aerobic respiration- carbon dioxide, water, and energy

Anaerobic respiration $–$ alcohol, carbon dioxide, and energy

# Question: 3

Where does anaerobic respiration take place in humans?

## Solution:

Anaerobic respiration in humans take place in muscle cells, during heavy exercise, when there is a temporary deficiency of oxygen.

# Question: 4

When you are feeling drowsy how does your body keep you awake?

## Solution:

When we are sleepy or drowsy the body keeps us awake by yawning, which takes in extra amount of oxygen and helps to provide more energy to the body.

# Question: 5

Why do frogs breath through both the skin and lungs?

## Solution:

Frogs need both lungs and skin to breathe because they are amphibians, and they can stay both in land and in water.

# Question: 6

How does a cockroach breath in and out?

## Solution:

Through spiracles

# Question: 1

What do you understand by cellular respiration?

## Solution:

Cellular respiration is the breaking down of food within cells with the release of energy. It takes place in all cells of living organisms.

# Question: 2

How does yeast respire?

## Solution:

Yeast is a living organism that can live without air. Such organisms are known as anaerobes and they derive energy through anaerobic respiration. In the absence of oxygen, food (glucose) breaks down to give alcohol and carbon dioxide.

# Question: 3

Why do you get muscle cramps after heavy exercise?

## Solution:

Muscle cramps occur when anaerobic respiration takes place in muscle cells. This results in a partial breakdown of glucose which produces lactic acid and the cramps are caused by the accumulation of lactic acid.

# Question: 4

Why does a massage or hot bath give relief from muscular cramps after running or heavy exercise?

## Solution:

A hot water bath or massage after heavy exercise helps to improve the blood circulation. The improved circulation helps to increase the oxygen supply to muscle cells, which in turn leads to a complete breakdown of the lactic acid into water and carbon dioxide.

# Question: 5

Why should we avoid over watering a potted plant?

## Solution:

We should avoid over watering a potted plant because the air spaces in soil would be filled with water. The root cells of plants like any other living cells also need oxygen to generate energy, and due to over watering it will be deprived of it owing to the water particles present between the soil that removes the air particles containing oxygen. Thus, due to lack of oxygen the roots will start rotting and the plant will slowly die if overwatering is not stopped.

# Question: 6

Give the percentage of oxygen and carbon dioxide in inhaled and exhaled air?

# Question: 7

Why does lime water turn milky when exhaled air is passed through it?

## Solution:

Lime water turns milky when exhaled air is passed through it because exhaled air contains carbon dioxide, which reacts with the lime water to produce calcium carbonate, which is deposited in the form of a white precipitate.

# Question: 1

Draw the human respiratory system and label each part.

## Solution:

Nasal Cavity:  The nose allows the air to enter and exit from the body. It consists of mucus which filters air the entering the body and warms it up to an appropriate temperature.

Mouth Cavity: Air enters the body from the mouth cavity.

Pharynx: Pharynx is the muscular tube that carries the air down into the windpipe.

Trachea: Trachea is the windpipe that takes air from the vocal cords to the lungs.

Lungs: Lungs are spongy air-filled organs located on both sides of the chest cavity. Lungs perform the major function by transferring oxygen into the blood stream and release of carbon dioxide into the air.

Ribs: Rib cage surrounds the lungs from the sides and protects them. It is flexible and expands or contract during the breathing process.

Diaphragm: The diaphragm controls breathing by contracting and relaxing. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs. It separates the chest cavity from the abdominal cavity.

# Question: 2

Show the mechanism of breathing through a diagram and label each part

## Solution:

1.         Inhalation:

During inhalation, the rib muscles contract and move up expanding the rib cage. The diaphragm contracts and moves down increasing the space in the chest cavity. Due to this the pressure inside the chest decreases and air is pushed into the lungs.

2.         Exhalation:

During exhalation, the rib muscles relax and move down contracting the rib cage. The diaphragm relaxes and moves upwards decreasing the space in the chest cavity. Since the pressure inside the chest increases, air is pushed out of the lungs.

# Question: 3

Explain the mechanism of respiration in cockroaches?

## Solution:

There are small openings on the sides of a cockroach known as spiracles through which the air is taken in and given out. There is a network of air tubes known as tracheae inside the body, which helps in the diffusion of air in the body. When oxygen rich air moves in through the spiracles, it first goes into the tracheal tubes, from where it diffuses into the various body tissues and cells. In the same way, carbon dioxide from the cells and tissues enter the tracheal tubes and goes out of the body through spiracles.

# Question: 4

How do fishes breathe under water?

## Solution:

The presence of gills in fish helps them in respiration by using the oxygen dissolved in water. Gills which are projections of the skin have supplies of blood vessels in them that are used in gaseous exchange. Water containing oxygen enters through the mouth, and water containing carbon dioxde is exhaled out through the opening of gills.

# Question: 5

Show how roots absorb oxygen through a diagram?

# Question: 6

How do we breathe?

## Solution:

Air enters our body through the nostrils. During inhalation the air moves through our nostrils and enters the nasal cavity. From the nasal cavity, it travels through the windpipe to reach our lungs. The lungs are protected by the ribs that form a cage on all sides, and there is a muscular sheet known as diaphragm at the bottom. Breathing is a mechanical process that involves the synchronised movement of the rib cage and the diaphragm. At the time of inhalation, the rib cage moves up and outwards while the diaphragm is pushed down, which creates more space in the chest cavity so that the air can easily move into the lungs. At the time of exhalation, the rib cage moves down and inwards, and diaphragm goes to its original position. Owing to this movement the chest cavity space decreases, and the air is automatically pushed out of our lungs.