Photosynthesis and Respiration Test - 2

Cellular respiration or respiration is the process by which cells breakdown glucose to release energy. Carbon dioxide and water are also released in the process. This can happen in the presence or absence of oxygen. When respiration takes place in the presence of oxygen, it is called aerobic respiration. If it happens in the absence of oxygen, it is called anaerobic respiration.

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.

Stomata are small pores present on the lower surface of green leaves of plants. They are responsible for the exchange of oxygen and carbon dioxide. Excess water is also removed from the plant through the stomata. This process is called transpiration.

The food we eat is digested into smaller particles. The nutrients like carbohydrates, proteins, fats, vitamins and minerals are absorbed into the blood which transports it to all parts of the body. Of these nutrients, glucose is taken up by cells and broken down to produce carbon dioxide and water with the release of energy. This energy is used to carry out all life processes. Carbon dioxide that is produced during this process is expelled out of the body during exhalation. 

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.

Earthworms breathe through their skin. Frogs, when present in water, breathe through the skin. This kind of exchange of gases is called as cutaneous respiration. In insects like cockroaches and grasshoppers, breathing takes place through a network of fine tubes called tracheae. Birds breathe through their lungs.

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

Spiracles are small external openings of trachea in insects. Trachea are a network of tubes responsible for gaseous exchange in insects. Cockroaches have spiracles on their exoskeleton which allow air to enter the trachea and help in respiration.

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%.