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Because the amount of dissolved O₂ in water, is less as compared to the air in the atmosphere.

Nerve, dendrite, cell body, axon, synapse, impulses, reflex action, nerve, muscle cell.

Soil is important for plants because it holds roots that provide support for plants and stores nutrients. Detective Le Plant is searching for secrets in the soil. Help him uncover the ingredients of soil that are important to plant growth.

Nutrition is an absolute necessity for the organisms because nutrition provides energy for carrying out metabolic activities.

Respiration occurs at the same rate in both day & night. But the difference is because of photosynthesis. During day time both respiration & photosynthesis occurs in plant. Both respiration & photosynthesis are opposite processes. In respiration, there is an intake of O₂ and release of CO₂, while in photosynthesis CO₂ is taken inside and O₂ is released. But the rate of photosynthesis is much higher than the rate of respiration. Due to this reason, release of O₂ is also much higher than release of CO₂. Since there is no net release of CO₂, it seems that no respiration occurs in plant.

(a) Oxygen.

(b) Carbon dioxide

(a) Waste.

(b) Nephron.

(c) Kidneys.

(d) Lymph.

(e) White, red

(a) Liver secretes bile which gets stored in the gall bladder. Bile performs two functions: 

(i) Makes the acidic food coming from the stomach alkaline so that the pancreatic enzymes can act on it. 

(ii) Bile salts breaks the fats present in the food into small globules making it easy for the enzymes to act and digest them. 

(b)Trypsin: It is a pancreatic enzyme present in the pancreatic juice. Its function is to digest the proteins.

(a) Liver secretes bile which gets stored in the gall bladder. Bile performs two functions:  

(i) Makes the acidic food coming from the stomach alkaline so that the pancreatic enzymes  can act on it.  

(ii) Bile salts breaks the fats present in the food into small globules making it easy for the  enzymes to act and digest them.  

(b) Trypsin: It is a pancreatic enzyme present in the pancreatic juice. Its function is to digest  the proteins.

Digestive enzymes.

Osmoregulation refers to the regulation of water and salt concentration across the membranes within the body fluid to maintain the required osmotic pressure. It serves to maintain the dissolved ions concentration of body fluid. 

(i) The main osmoregulatory organs in humans are kidneys. They also function to filter blood. 

(ii) Amoeba possesses contractile vacuoles as osmoregulatory organs. It serves to regulate the water content of the cell. These vacuoles help the amoeba to survive in hypertonic as well as hypotonic environment.

Correct option (D) (i), (ii), (iii) and (iv)

Explanation: 

Transpiration is the loss of water in the form of vapour from the living tissues of aerial parts of the plant. lt mainly occurs by the process of diffusion through stomata.

It is regarded as 'necessary evil' due to some of the following advantages and disadvantages. 

Advantages :

(i) Transpirational pull created by transpiration of water from leaf surface causes ascent of sap (upward movement of water and mineral salts). 

(ii) The sap absorbed from the soil contains low concentration of mineral salts. The loss of water through transpiration increases the concentration of mineral salts in the plant. 

(iii) Due to the heat of the Sun, temperature of the plant increases which may be harmful for the plants. Transpiration lowers down the temperature of the plant by 10° - 1 5°C.

Disadvantages :

Due to transpiration being higher than the rate of water absorption at noon time wilting or loss of turgidity is quite common. Excess dehydration reduces the rate of photosynthesis and other metabolic activities, which may further lead to injury in plants.

Root hair is the name of the extensions of the epidermal cells of a root which help in respiration.

(a) Respiration in roots: The roots of a plant take the oxygen required for respiration from the air present in-between the soil particles by the process of diffusion. The roots have extensions of epidermal cells of a root called root hair which are in contact with the air in the soil. Oxygen diffuses from root hairs and reaches all the other cells of the root for respiration. Carbon dioxide gas produced in the cells of the root during respiration moves out through the root hairs by the process of diffusion. Thus, the respiration in roots occurs by diffusion of respiratory gases through the root hairs. 

(b) Respiration in stems: The stems of herbaceous plants takes place through stomata. The oxygen from the air diffuses into the stem of a herbaceous plant through stomata and reaches all the cells for respiration. The carbon dioxide produced diffuses out through stomata. In woody stems, the bark has lenticels for the exchange of gases. 

(c) Respiration in leaves: The leaves of a plant has tiny pores called stomata through which the exchange of respiratory gases takes place by diffusion. Oxygen from air diffuses into a leaf through stomata and reaches all the cells, where it is used for respiration and the carbon dioxide produced diffuses out from the leaf into the air through stomata.

Translocation is the movement of soluble materials, products of photosynthesis from leaves to other tissues throughout the plant.

Respiration uses O₂ and releases CO₂ but in photosynthesis,CO₂ is used and O₂ is released. 

Leaves is chlorophyll mainly present in a plant.

(a) Chlorophyll. 

(b) Green.

Chloroplast.

Diffusion is a phenomenon explaining movement of substances from its higher concentration to its lower concentration. In plants, diffusion of gases occurs. 

Factors affecting diffusion are:-

(i) Concentration gradient:- More steeper the concentration gradient, greater will be the diffusion. 

(ii) Temperature:- Diffusion rate increase with increase in the temperature because speed of ions increases. 

(iii) Size of molecules:- Molecules with smaller size can diffuse easily as compared to molecules with larger size.

During day time, both respiration and photosynthesis occurs in plant. Both respiration & photosynthesis are opposite processes. In respiration, there is an intake of O₂ and release of CO₂, while in photosynthesis CO₂ is taken inside and O₂ is released. But the rate of photosynthesis is much higher than the rate of respiration. Due to this reason, release of O₂ is also much higher than release of CO₂.

The respiratory surface of animals must always be moist for better diffusion of gases. Both oxygen and carbon-dioxide gets dissolved in water quickly and their diffusion becomes easier & quicker. This is the reason for moist respiratory surfaces.

Correct option  (C) Adrenaline

Explanation: 

Adrenaline is secreted in small amount in normal situation but when a person faces stress or danger, it is secreted in large amount to prepare the body for emergency and stress condition such as facing an interview. Large amounts of adrenaline causes increase in heart beat to supply more oxygen to muscles. The breathing rate also increases due to the contraction of the diaphragm and rib muscles. Also, basal metabolic rate, blood pressure and sugar level in blood is increased. Because of its roles in emergency situations, adrenaline is also called emergency hormone.

Correct option  (C) Grana, Stroma 

Explanation: 

Photosynthesis occurs in two phases: light phase and dark phase. ln chloroplast, light phase takes place in grana while dark phase occurs in stroma

Stomata in the leaves and lenticels in the stems are two parts through which a plant releases its gaseous waste products into the air.

(a) The opening and closing of stomatal pores is controlled by the guard cells, when water flows into the guard cells, they swell, become curved and cause the pore to open whereas when the guard cells lose water, they shrink, become straight and close the stomatal pore. 

(b) Plant kept in continuous light will live longer because it will be able to produce oxygen required for its respiration by the process of photosynthesis.

• Plant kept in continuous light live longer because plats release CO₂ during respiration. 
• In case of plant kept in dark CO₂ resulting in lack of oxygen and the plant will die earlier.

Function of the Hypothalamus

The hypothalamus is vital for the maintenance of homeostasis through the coordination of autonomic, endocrine, and somatic behavior. To achieve this, a series of processes occur.

Firstly, the hypothalamus plays a role in the autonomic nervous system. It processes sensory impulses received from the smooth muscle within the body which lines organs such as the intestines and stomach, as well as blood vessels. By processing the impulses, the hypothalamus is able to regulate the movement of food, heart rate, and the contraction of the bladder.

Furthermore, the hypothalamus is considered by some to be the vital interaction between the body’s central systems: the endocrine system which is responsible for regulating bodily states by releasing hormones; and the nervous system which coordinates and sends synaptic information. The hypothalamus detects changes within the body and coordinates responses by stimulating the release of hormones from organs and glands. These pathways enable the hypothalamus to regulate a series of processes within the body.

(a) Anaerobic respiration in yeast.

(b) Aerobic respiration in humans.

(c) Anaerobic respiration in muscle tissue of animals.

1.b. Kidney

2.c. Lungs

3.a. Renal artery

4.a. Nephrons

5.b. Renal vein

(a) Aquatic animals are the animals which live in water and the terrestrial animals are the  animals which live on land.  

(b) The aquatic animals use the oxygen dissolved in water to carry out respiration. The  terrestrial animals obtain oxygen from air.

Fishes die when taken out of water because they do not have lungs to utilize the oxygen of air for breathing and respiration. They have gills which can extract only dissolved oxygen from water.

In humans, lungs are the major respiratory organ. Internally, lungs are divided into numerous sac like structures called as alveoli. These alveoli (sing. alveolus) are thin walled and are the major site for exchange of gases. They take up carbon dioxide from the deoxygenated blood and fill it with oxygen.

Oesophagus is the other name of food pipe.

(a) Digestive system:

• The digestive system is responsible for digestion of food. i.e. breaking down complex insoluble food into simpler soluble form. 
• The digestive system is made up of alimentary canal and digestive glands. 
• The alimentary canal is a long and muscular tube of varying diameter which extends from the mouth to the anus. 
• The digestive glands associated with alimentary canal are salivary glands, gastric glands, liver and pancreas. 
• The process of digestion includes various stages wherein the food passes through the different organs of the alimentary canal and there it is digested part by part with the help of various enzymes secreted from the digestive glands.
• After the food is digested, the important nutrients are absorbed into the blood and the undigested food and residue of digested food is removed out of the body through the anus.

(b) Respiratory system:

• Respiration is the process of release of energy from the assimilated food. 
• The respiratory system consists of nose, pharynx, larynx, trachea, bronchi and lungs (alveoli). 
• Oxygen enters our body through breathing. 
• This oxygen is taken to the cells and with the help of oxygen, food is oxidized into the cells to release energy in the form of ATR.
• During this process, carbon dioxide and water vapour are given out as by-products which are given out during breathing.

Thus, the digestive and respiratory systems work in co-ordination with each other to produce energy from food.

Trachea is the other name of wind-pipe.

Alveoli in the lungs does gas exchange take place.

Alveoli in the lungs.

The correct answer is Alveoli

Respiratory pigments play a very important role in the body of an organism. It helps in the transportation of respiratory gases to the various body organs. 

Respiratory pigment present in humans is haemoglobin. It is a red color pigment present in our blood. It helps in transporting oxygen from lungs to various body tissues and also helps in the removal of carbon-dioxide from cells.

The process of movement of water in the plants through xylem and its evaporation through leaves or stem is known as transpiration. Transpiration supplies water for photosynthesis, cools the leaves surface through evaporation, and the transpirational pull helps in transportation of minerals from the roots to the leaves. But it never helps in the translocation of sugars. Translocation is the process of movement of food from the leaves to the different parts of the plant through phloem.

The deoxygenated blood collected from different body parts is poured into the right auricle. From right auricle it moves to the right ventricle and through the pulmonary artery this is deoxygenated blood is pumped into the lungs where it is oxygenated. Then this oxygenated blood is transported to the left Atrium and then moves to the left ventricle from where it is pumped into the whole body.

(a) In plants, there are tiny pores called stomata on leaves and lenticels in stem which facilitate the exchange of gases. CO₂ is taken in and O₂ given out (during photosynthesis) and vice-versa during respiration. 

(b) Mechanism of Transport of Water and Minerals in a Plant 

• The vessels and tracheids of roots, stems and leaves in xylem tissue are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant. 

• The cells of the roots in contact with the soil actively take up ions which creates a difference in the ion concentration between the root and the soil. 

• Thus, there is steady movement of water into root xylem from the soil, creating a column of water that is pushed upwards. 

• Plant uses another strategy to move water in the xylem upwards to the highest points of the plant body. 

• The water which is lost through the stomata is replaced by water from the xylem vessels in the leaf. 

• Evaporation of water molecules from the cells of a leaf creates a suction which pulls water from the xylem cells of roots. 

• This loss of water is transpiration which helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. 

• Transpiration becomes the major driving force in movement of water in the xylem during the day when the stomata are open. 

• This mechanism is also known as cohesion of water theory or transpiration pull. 

Aerobic respiration.

No all cells use oxygen to produce energy.

Translocation is the process of movement of carbohydrates (which act as food) produced by the leaves which is to be distributed to different parts of the plant. The process of translocation takes place in the phloem cells. Thus the cell involved would be companion cells, sieve elements & parenchymatous tissue.

Xylem and phloem are the conducting structures which are present in plants. Xylem is responsible for transportation of water and minerals whereas phloem is responsible for translocation of food.