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D) CO₂ + Water + Energy

The CO₂H₂O and energy (ATP).

Anaerobic respiration taking place in bacteria and fungi, in which glucose is oxidized into alcohol and CO₂ or some organic acid, is called fermentation.

Factors affecting respiration are divided into two categories. 

(1) External or environmental factors 

(2) Internal or plant factors. 

(1) External factors 

• Temperature
• Oxygen
• Water
• Light 
• Carbon dioxide 

(2) Internal factors 

• Protoplasm
• Respiratory substrate
• Age of Cell 
• Wound and injury 

1. External factors or Environmental Factors: 

1. Temperature: It is the most important factor affecting the rate of respiration. Normally the rate of respiration increases to a certain limit by an increase in temperature from 5.0°C to 30.0°C. In this range, the rate of respiration increases as per Vont Hoff’s rule. According to this a rise in temperature by 10°C, the rate of respiration becomes double. Increase in temperature beyond 35.0°C results into decrease in rate as the enzymes begin to denaturalize. At very low temperatures also enzymes become inactive and the rate of respiration decreases. In cold storage, the fruits and vegetables escape spoilage because of this. 

2. Oxygen: Oxygen is necessary for aerobic respiration because it acts as a terminal acceptor of electrons. At low concentration of oxygen both aerobic and anaerobic respiration may take place, but when the concentration of oxygen becomes zero only anaerobic respiration takes place. Under such a condition value of R.Q. becomes infinite (∞)

3.Water: Water acts as a medium for all metabolic activities. The protoplasm contains up to 90-95% of water. Water plays an important role in enzyme activation, gaseous diffusion, transportation etc. In dry seeds and fruits rate of respiration is extremely low due to the shortage of water and so these can be stored for a long duration. In the presence of water stored carbohydrates convert into soluble sugar and the rate of respiration increases. 

4. Light: Rate of respiration is not influenced directly by light and so it takes place in the presence as well as an absence of light.

5. Carbon dioxide (CO₂): Increase in concentration of CO₂ inhibits respiration. Hence it has an adverse effect on the germination of seeds and rate of growth of plants. Heath experimentally proved that an increase in the concentration of CO₂ causes the closure of stomata and the rate of respiration decreases due to a shortage of oxygen. 

Internal factors or Plant Factors: 

1. Protoplasm: Meristematic cells have dense and active cytoplasm and so the rate of respiration is relatively high in these cells as compared to the mature cells. The activity of protoplasm is affected by several factors such as hydration, pH, temperature etc. 

2. Respiratory substrate: Different types of sugars such as glucose, fructose, maltose etc. present in the cell are quickly used in respiration. In comparison to these starch and fats need to be first converted into a soluble form and only then they can be used as a respiratory substrate. This is the reason why in hospitals a patient is administered directly with, glucose, whereas the normal diet of healthy persons contains starch and fats.

3. Age of Cells: The rate of respiration is much higher in the young cells as compared to mature and old cells. 

4. Wound and Injured part: Rate of respiration sharply increases in the wound and injured part to promote healing.

Ethyl alcohol and CO₂ or Lactic acid, Acetic acid, Butyric acid etc.

1. Fermentation: Anaerobic respiration taking place in bacteria and fungi, in which glucose is incompletely oxidized into alcohol and CO₂ or organic acid is called fermentation. 

2. Oxidative break-down of pyruvic acid: Pyruvic acid formed as an end product of glycolysis enters mitochondria and in the matrix region of mitochondria, it is completely oxidized into CO₂ and H₂O in the presence of oxygen. This is called an oxidative breakdown of pyruvic acid. Before entry into mitochondria, pyruvic acid is converted into Acetyl Coenzyme-A by decarboxylation and dehydrogenase enzyme. This complex reaction is catalyzed by five co-factors. These are Coenzyme A; NAD⁺ ; Mg⁺⁺; Thymine pyrophosphate (TPP) and Lipoic acid. Acetyl Coenzyme – A formed in this reaction acts as a connecting link between glycolysis and Krebs cycle. 

3. Respiratory Quotient: The ratio of the volume of CO₂ released in respiration to the volume of O₂ used is called respiratory quotient. 

The value of R.Q. of different respiratory substrates is as follows: 

R.Q. of carbohydrate = 1.0 

R.Q. of fats = 0.7 

R.Q. of proteins = 0.8 

R.Q. of organic acids = 1.33 

R.Q. of succulents = zero Anaerobic respiration 

R.Q. = infinite (∝). 

4. Chemiosmotic theory of Mitchell: This theory was proposed by Mitchell to explain ATP formation during respiration and photosynthetic process. According to this theory, transport of positively charged protons (Hydrogen ions) across the membrane of mitochondria or chloroplasts takes place through the enzymes involved in these processes via an electron transport system. Due to this, the electrochemical gradient is created on two sides of the membrane.

• High energy-containing complex organic compounds oxidized during respiration are called respiratory substrates. 
• Example: Carbohydrates, fats proteins etc.

The respiratory quotient is the ratio of the volume of CO₂ released to the volume of O₂ used in respiration. It can be represented as

Peter Mitchell proposed the chemiosmotic theory.

The answer is (c) Mitchell

Pentose phosphate path is an alternative path for complete oxidation of glucose. In this process hexose sugar is oxidized through the involvement of a five carbon-containing sugar, hence it is called a pentose phosphate path. 

Racker and coworkers (1954) studied details of pentose phosphate path. The reactions of PPP take place in the presence of oxygen. This process is completed in the cytoplasm of the cell. The main steps of PPP are as follows: 

• Phosphorylation of glucose.
• Oxidation of glucose 6-phosphate.
• Oxidative decarboxylation of phosphoglucose acid and formation of ribulose-5 phosphate.
• A complete break down of ribulose – 5 phosphates through several reactions.

The answer is (c) α-ketoglutaric acid

The answer is (c) Cytoplasm

The answer is (d) Two

Respiratory organs in earthworm skin

Pleura are the two membranes that protect lungs from injury.

(d) bronchioles are without cartilaginous rings

The lungs are covered by double layered pleural membrane containing several layers of elastic connective tissues and capillaries. It encloses the pleural fluid which reduces friction when the lungs expand and contract.

Correct Answer is : (b) sternum

(c) Simple diffusion

The lungs are light spongy tissues enclosed in the thoracic cavity surrounded by an air tight space. It is bound dorsally by the vertebral column and ventrally by the sternum, laterally by the ribs and on the lower side by the dome shaped diaphragm.

The ciliated epithelial cells lining the trachea, bronchi and bronchioles secrete Mucus.

The diffusion membrane of the alveolus is made up of three layers. 

They are:

• The thin squamous epithelial cells of the alveoli. 
• The endothelium of the alveolar capillaries and 
• The basement substance found in between them.

The thin squamous epithelial cells of the alveoli are composed of Type I and Type II cells. Type I cells are very thin so that gases can diffuse rigidly through them. Type II cells are thicker. They synthesize and secrete a substance called surfactant. It lowers the surface tension in the alveoli and prevents pulmonary edema.

(b) emphysema

Correct Answer is : (a) high pCO₂

A molecule of haemoglobin carries how many oxygen molecules 4.

(d) carbaminohaemoglobin

(d) Oxygen content in arterial blood

Oxygen haemoglobin dissociation curve will shift to right on decrease of pH.

Correct Answer is : (b) four

(b) Move to right