Science [2 Mark Questions]

Plants need nitrogen to make proteins and other compounds. They take up nitrogen from the soil in the form of inorganic salts called nitrates (or nitrites), or in the form of organic compounds which are produced by bacteria from the atmospheric nitrogen.

Oxygen enters the body through the nose and mouth passes through the larynx and the trachea.
As shown in the diagram given below:

Pseudopods are actually extensions of the cytoplasm, or the thick liquid that is inside organisms like amoeba. The organism can change the shape of the pseudopod, making it move, appear, and disappear.
Pseudopodia (singular: pseudopodium) are temporary finger-like elongated protrusions of cell surface of unicellular organisms (Amoeba) used for feeding and locomotion. They are formed by cytoplasmic streaming (streaming movement of cytoplasm). It is also called as false foot.

1. Trypsin: Proteins, peptones and proteoses.
2. Amylase: Starch, dextrins.
3. Pepsin: Proteins.
4. Lipase: Fats.

1. Three chambered heart.
2. Four chambered heart.
3. Two chambered heart.

Several proteases are synthesized in the pancreas and secreted into the lumen of the small intestine. The two major pancreatic proteases are trypsin and chymotrypsin. Trypsin and chymotrypsin digest proteins into peptides and peptides into smaller peptides, but they cannot digest proteins and peptides to single amino acids. Some of the other proteases from the pancreas, for instance carboxypeptidase, have that ability. The final digestion of peptides into amino acids is largely done in small intestine.

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

Parasitic nutrition is a mode of heterotrophic nutrition where an organism lives onthe body surface or inside the body of another type of organism. The parasiteobtains nutrition directly from the body of the host. The parasites derive their nourishment from their host. Parasitic organisms like tapeworms, leeches, orchids, etc.

The major organs of respiratory system in human beings are:

1. Nose.
2. Nasal Passage.
3. Trachea.
4. Bronchi.
5. Lungs.
6. Diaphragm.

Saprophyte: Saprophytes are the organisms which obtain their food from dead plants (like rotten leaves), dead and decaying animal bodies, and other decaying organic matter (like rotten bread).
Example: Fungi and some bacteria.

The soft stems of small herbaceous plants have stomata in them and hard stem of big plants and trees have lenticels in them. Lenticels are in the small area of a bark. These cells are loosely placed and therefore allow the gaseous exchange of respiratory gases between air and living cells of the woody stem. Stomata help in the gaseous exchange of respiratory gases between stems of herbaceous plants and air. It is through stomata that oxygen from air diffuses into the stem and goes to all the cells of a stem for respiration. Similarly, carbon dioxide produced in the stems diffuses into stomata of herbaceous plants and lenticels of trees or large plants and goes out into the air.

Nutrition: Nutrition is defined as a process of intake of nutrients (like carbohydrates, fats, proteins, minerals, vitamins and water) by an organism as well as the utilisation of these nutrients by the organism. Nutrition is necessary for an organism as it provides energy to them from the food they eat.

Another type of circulatory fluid in the human body is the lymph. lymph flows through lymphatic vessels. Lymph destroys the invading microorganisms and foreign particles in the lymph nodes. lymph is colourless liquid which is formed out of blood plasma.

Here, A, B, C, D, E, F and G refer to the nose, nostrils, trachea, bronchi, lungs, bronchioles and alveoli, respectively.

1. Anaerobic respiration.
2. Aerobic respiration.

Hydrochloric acid: It makes the medium of gastric juice acidic so that the enzyme pepsin can digest the proteins properly and also kills any bacteria that might have entered the stomach with food.

Humans need oxygen for surviving. In the sea the solubility of oxygen is very low which is not sufficient for humans. Therefore the divers carry oxygen in order to survive in water for longer time.

Both of them involve exchange of gases through stomata.
Transpiration is the evaporation of excess water from leaves. This happens when the guard cells are open to facilitate gaseous exchange.
Respiration is a process that happens all the time. In the day as well as in the night as it is vital for the life of a plant.

The urine is made up of a number of constituents. Urine is an aqueous solution of greater than 95% water. Other constituents include urea, chloride, sodium, potassium, creatinine and other dissolved ions, and inorganic and organic compounds. Urea is a non-toxic molecule made of toxic ammonia and carbon dioxide.

The measurement of a person’s blood pressure is recorded as two different numbers the systolic blood pressure and the diastolic blood pressure.
These two numbers reflect different aspects of the pressure being exerted by your blood as it pulses through your arteries. Both the systolic and diastolic pressures are important. The systolic and diastolic pressure of a normal man is 120/ 80mm Hg. In this, 120mm Hg represents the systolic pressure whereas 80mmHg represents the diastolic pressure.
If the readings are too high, hypertension may be present. If the blood pressure readings are too low, there may be insufficient blood flow to critical organs, such as the brain.

Exhaled air contains more carbon dioxide because during the respiration process when oxygen breaks down glucose, then a lot of carbon-dioxide is produced hence the exhaled air has a higher proportion of the same.

The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organism and hormone such as Anti-diuretic hormone (ADH) also regulates the amount of urine produced.

Blood clotting means changing state of blood into solid or gel form also called coagulation. this mainly occur when blood are contact with air. blood contain two cells fibrin and platelets, which take gel form when open to air.

Platelets are tiny blood cells that help your body form clots to stop bleeding. If one of your blood vessels gets damaged, it sends out signals to the platelets. they form a plug (clot) to fix the damage. The process of spreading across the surface of a damaged blood vessel to stop bleeding is called adhesion.

The latex is exuded as a waste product from plants. The tyres are made from the latex of rubber tree (Hevea brasiliensis). Hevea because the milky latex extracted from the tree is the primary source of natural rubber.

The rate of breathing increases during vigorous exercise. This is because the body needs more energy which can be released only if greater amounts of oxygen reach the cells. For this purpose, the rate of breathing increases. (This will increase the supply of oxygen to the cells). (However, after a while this strategy is also insufficient to meet the cell's need. This is because, there is a temporary shortage of oxygen being delivered to the working muscles. So muscles begin to respire anaerobically. Lactic acid is a by-product of producing energy anaerobically. When lactic acid accumulates at high levels in the blood, it causes muscular fatigue).

Respiration and photosynthesis are the two vital processes for plant life. The plant kept in light would be able to produce oxygen, required for respiration, by the process of photosynthesis and would live longer. The one kept in dark would die as soon as the container becomes filled with carbon dioxide gas produced by respiration.

The excretory system of human beings consists of the following main organs:
Two kidneys, two ureters, bladder and urethra.

Haemoglobin is a pigment present in RBC. It has a high affinity for oxygen. It carries oxygen from lungs to various tissues which are deficient in oxygen. Presence of less hemoglobin will result in less supply of oxygen to tissues. A person having less hemoglobin will get tired soon and will have a pale look.

In green plants, the carbon dioxide released during respiration gets utilized during photosynthesis. Oxygen is a by product generated during photosynthesis, and exits through stomata, root cell walls, and other routes. Plants can get rid of excess water by transpiration and guttation.

Parasitic nutrition: It is that nutrition in which an organism derives its food from the body of another living organism (called its host) without killing it.
Example: Plasmodium and round worms obtain food by parasitic nutrition.

Lenticels are pore-like openings seen on the surface of the stem. During periderm formation the cork cells becomes impervious to water and gases. To overcome this lenticels are developed during the secondary growth. They are meant for gaseous exchange.

The mode of nutrition in "Round worm" and "Plasmodium" is parasitic nutrition.

It is dangerous to inhale air containing carbon monoxide as it binds very strongly with haemoglobin in the blood and prevents it from carrying oxygen to the brain and other parts of the body. Due to lack of oxygen, the person cannot breathe properly and may become unconscious or may even die.

	Lymphatic capillaries	Blood capillaries
1.	They are related to transportation of lymph.	They are related to transportation of blood.
2.	Lymph flows in lymphatic capillaries.	Blood flows with more pressure in blood capillaries as compared to lymph capillaries.
3.	They are not visible due to colourless nature of lymph.	They are visible due to red colour of blood.

Human heart has four completely separated chambers which allow two completely separated circuits of oxygenated and deoxygenated blood i.e. double circulation.

1. It ensures complete separation of oxygenated and deoxygenated blood.
2. It allows rapid pumping of oxygenated blood under high pressure which is required by active endothermic animals to maintain the constant body temperature.

The role of the respiratory pigment is primarily to aid in the transport of molecular oxygen and thus help in respiration. A respiratory pigment is any molecule that increases the oxygen. In humans and most other vertebrates, the most common respiratory pigment is a protein the red blood cells in our blood can carry to our tissues and organs is called hemoglobin. It helps in transporting oxygen from lungs to various body tissues and also helps in the removal of carbon-dioxide from cells.

Respiration is a vital function of the body as it provides energy for carrying out all the life processes which are necessary to keep the organism alive.

1. Pepsin initiates the breakdown of proteins in stomach. Gastric lipase is another enzyme secreted by gastric gland.
2. If pancreatic duct is blocked then their will be no enzyme for protein and carbohydrates digestion. It may cause gain in weight.

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.

Special tissues and organs are needed for the transport of substances in plants and animals because these tissues and organs can pick up the essential substances like food, oxygen, water, etc at one end of their body and carry them to all other parts.

If leaves of a healthy potted plant are coated with Vaseline, it will clog the stomatal pores on leaves. Blockage of stomata will stop transpiration and exchange of gases from leaves. Transpiration plays an important role in ascent of sap in plants. Hence, lack of transpiration will stop ascent of sap. Moreover, stoppage of exchange of gases would also stop respiration and photosynthesis in leaves. This will result in death of leaves and finally the plant would die due to lack of food.

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.

Transport in organisms (plants and animals) is necessary as it absorbs all essential substances and transports them to all parts so that they reach each and every cell of the body.

Translocation is defined as “the transport of soluble products of photosynthesis”. The translocation in plants takes place by vascular tissue called phloem. The translocation is essential since without it, food prepared by leaves of plants could not reach other parts of plant.

1. In plants, synthesis of sugars occur in leaves by photosynthesis.
2. The hormones are synthesised away from their target site in plants.

Excretion in Amoeba: In amoeba, the waste material carbon-dioxide is removed by diffusion through the cell membrane, but nitrogenous waste and excess water are removed by contractile vacuole.

Chlorophyll is a green coloured pigment present in the leaves of plants. It helps in absorbing energy from sunlight during the process of photosynthesis.

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

1. Makes the acidic food coming from the stomach alkaline so that the pancreatic enzymes can act on it.
2. Bile salts breaks the fats present in the food into small globules making it easy for the enzymes to act and digest them.

If the teeth are not cleaned regularly, they become covered with the sticky, yellowish layer of food particles and bacteria cells called dental plaque. It causes tooth decay. It can be prevented by brushing the teeth regularly as it neutralises the acids.