Free Respiration in Organisms 02 Practice Test - 7th grade
Question 1
The floor of the chest cavity has a thick muscular partition known as the diaphragm.
SOLUTION
Solution : A
- The floor of the chest cavity has a thick muscular partition known as the diaphragm. It separates the abdominal cavity and the thoracic cavity.
- It performs a significant function in respiration. It moves up and down during inhalation and exhalation.
- Lowering of the diaphragm causes a decrease in the pressure on lungs. Due to which, air moves into the lungs through nose.
- When diaphragm rises up, pressure on the lungs increases. Due to which, air moves out.
Question 2
A cockroach has small openings on the sides of its body called _______.
SOLUTION
Solution : B
Cockroach has small openings on the sides of its body called spiracles. Oxygen rich air rushes through the spiracles into the tracheal tubes. It then diffuses into the body tissue and reaches all the cells of the body. Carbon dioxide from the cells goes into the tracheal tubes and ultimately moves out through the spiracles.
Question 3
In human body, lungs are located in the _____ cavity.
SOLUTION
Solution : A and B
Humans have a pair of lungs situated in the chest cavity. The chest cavity is also known as thoracic cavity. Each lung has double layered covering called pleura. The thoracic cavity is separated from abdominal cavity by a muscular structure called diaphragm.
Question 4
Cells breakdown ________ using oxygen, to produce water, carbon dioxide and energy.
SOLUTION
Solution : D
Cells breakdown glucose to produce water and carbon dioxide. Energy is released in the form of ATP. This process is called cellular respiration. When this process happens in the presence of oxygen, it is called aerobic respiration and when it happens in the absence of oxygen, it is called anaerobic respiration.
It can be summarised as:
C6H12O6+6O2→6CO2+6H2O+38 ATP
Question 5
The accumulation of lactic acid in muscle cells causes ______.
cramps
heart blockage
boils
stroke
SOLUTION
Solution : A
Lactic acid is a byproduct of anaerobic respiration of glucose. During heavy exercises or prolonged physical activity, there is a deficit of oxygen required to enable all the muscle cells to generate energy aerobically. Muscle cells then respire anaerobically and produces lactic acid. Accumulation of lactic acid in the muscles causes cramps.
Question 6
What is the percentage of carbon dioxide in exhaled air?
21%
0.04%
4.4%
16.4%
SOLUTION
Solution : C
The percentage of carbon dioxide in exhaled air is more than that of the percentage of carbon dioxide in the inhaled air. Inhaled air has about 0.04% of carbon dioxide. This is also the amount of carbon dioxide present in the atmosphere. The exhaled air contains all the carbon dioxide that is a by product of the cellular metabolic processes. Hence, the percentage of carbon dioxide in the exhaled air is 4.4%.
Question 7
The energy stored in food is released during _____.
circulation
digestion
respiration
excretion
SOLUTION
Solution : C
- Digestion breaks down the complex carbohydrates into simple glucose units. The glucose molecules are further broken down to release energy in respiration.
- During cellular respiration, glucose is further broken down into carbon dioxide and water with the help of oxygen and energy is released in the form of ATP. It can be summarised as:
C6H12O6+6O2→6CO2+6H2O+38 ATP
- Circulatory system performs the function of transport of various substances like water, hormones, oxygen, etc.
- Excretion refers to the elimination of waste products from the body.
Question 8
Which gas is used during the process of aerobic cellular respiration?
SOLUTION
Solution : A
Oxygen is required during the process of aerobic cellular respiration in the cell. Aerobic respiration is a process which utilises oxygen to breakdown glucose into carbon dioxide and water and release energy in the form of ATP.
It can be summarised as:
C6H12O6+6O2→6CO2+6H2O+38 ATP
Question 9
The product of anaerobic respiration in muscles is:
Alcohol
Lactic acid
Water
Carbon dioxide
SOLUTION
Solution : B
Our muscles generally respire aerobically. During heavy exercises, the demand for energy in these cells are high but the supply of oxygen to produce energy is limited. In such situations, the muscle cells turn to anaerobic respiration to fulfil the energy demands. The anaerobic breakdown of glucose produces lactic acid in muscles.
Question 10
Frogs breathe through their ________ under water.
SOLUTION
Solution : B
∙ Amphibians like frogs breathe through their skin when they are submerged in water. This is called cutaneous respiration. In the land, they breathe through their lungs.
∙ Gills are present in fishes.
∙ Trachea is the site of gaseous exchange in insects.
∙ All mammals have lungs to breathe.