Science [5 marks Questions]

1.  

2. The glucose that enters the nephron along with the filtrate get absorbed by the glomerulus goes to the proximal convoluted tubule (pct) and again reabsorbed and enters the blood.

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2. To transport oxygen to each and every tissue and cell of the body along with circulation of the blood.

Maximum amount of oxygen is supplied to the cells and tissues as oxy-genated blood does not mix with the deoxygenated blood.

1. The three events that occur during the process of photosynthesis are:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

Role of stomata These help in the gaseous exchange between the plant and its atmosphere. Thus, it assists in supply of carbon dioxide, essential for photosynthesis.

2. Sunlight is essential for photosynthesis:

Place a healthy green potted plant in a dark room for 1-2 days. This is done to ensure that the plant consumes all its reserve food and the leaves do not contain any starch. Then, cover a portion of a leaf of this plant on both sides with two uniform pieces of black paper, fixed in position with two paper clips.

Now, expose this plant to bright light. After a few hours, remove the leaf, decolorize it with alcohol, and test the presence of food (starch) with iodine solution.

You will observe that the portion of the leaf covered with black paper does not show any presence of starch (food).

Explanation of the activity:

The food prepared by plants (carbohydrates) through the process of photosynthesis is stored as starch. This starch reacts with the iodine solution to change to blue-black colour. Only those portions of the leaf that were exposed to sunlight could photosynthesize and hence, change to blue-black colour when tested with iodine.

1.  

2. Functions of the kidney:

1. Maintaining overall fluid balance.
2. Regulating and filtering minerals from blood.
3. Filtering waste materials from food, medications, and toxic substances.
4. Creating hormones that help produce red blood cells, promote bone health, and regulate blood pressure.

1.  

2. Role of liver–

• Liver helps to secrete bile juice for the digestion of food.
• Liver secretes Emulsification of fats.

Role of Pancreas–

• It secrets Pancreatic Juice/ Secretes glucagon/Insulin/Trypsin/Lipase
• Pancreas secretes pancreatic enzymes to digest proteins, carbohydrates and fats.

3.  

• Absorption of digested food is in Small intestine villi/ part of intestine
• Absorption of water is in Large intestine/ Colon.

1. Components of blood: Plasma and blood cells (corpuscles)
2. Movement of oxygenated blood in the body:

3. Valves present in between atria and ventricles help to restrict the backflow of the blood from the ventricle to the atrium when the ventricle contracts.
4. Differences between artery and vein:

	Artery	Vein
1.	It has thick elastic muscular walls.	It has thin, non-elastic walls.
2.	It does not contain valves.	It contains valves to prevent the backflow of blood.
3.	Blood flows under high pressure.	Blood flows under low pressure.

1. Excretion is the process of removal of harmful and unwanted substances, especially nitrogenous wastes, from the body.
2. Nephron is the basic filtration unit of the kidneys.
3.  

1. Kidneys: Form urine.
2. Ureter: Long tube which collects urine from the kidney.
3. Urinary bladder: Stores urine until it is passed out.

1. Oxygen.

• Released by splitting of water molecules.

2.  

• Tiny pores present on the surface of leaves.
• Opening and closing of stomata is a function of guard cells.
• Guard cells swell up, when water flows into them, causing the stomatal pore to open. If the guard cells shrink the pore closes.

1.  

2.  

• Digestion of flood is completed in small intestine only.
• Finger like projections (villi) in the wall of small intestine provides large surface area for maximum absorption.
• Villi of small intestine are richly supplied with blood vessels for carrying absorbed food to different parts of the body.

1. Organs that form the excretory system in human beings are- Pair of kidneys, a urinary bladder, a pair of ureters and a Urethra.
2. Urine formation is carried out by the excretory system. The nephrons play a major role in this. They carry out urine formation in various steps like glomerular filtration, selective reabsorption and tubular secretion.

1. Each nephron has a glomerulus, the site of blood filtration. The glomerulus is a network of capillaries surrounded by a cuplike structure, the glomerular capsule (or Bowman’s capsule). As blood flows through the glomerulus, blood pressure pushes water and solutes from the capillaries into the capsule through a filtration membrane. This glomerular filtration begins the urine formation process.
2. Inside the glomerulus, blood pressure pushes fluid from capillaries into the glomerular capsule through a specialized layer of cells. This layer, the filtration membrane, allows water and small solutes to pass but blocks blood cells and large proteins. Those components remain in the bloodstream. The filtrate flows from the glomerular capsule further into the nephron.
3. The resulting filtrate contains waste, but also other substances the body needs: essential ions, glucose, amino acids, and smaller proteins. When the filtrate exits the glomerulus, it flows into a duct in the nephron called the renal tubule.
4. Waste ions and hydrogen ions pass from the capillaries into the renal tubule. This process is called secretion. The secreted ions combine with the remaining filtrate and become urine. The urine flows out of the nephron tubule into a collecting duct. It passes out of the kidney and down to the bladder.

Urine is a liquid or water waste product that passes through your urinary tract and is expelled from your body through your urethra. It contains 90-95% water.

The artificial kidney contains tubes made of cellophane with a semi-permeable lining. These tubes are suspended in a tank filled with a dialyzing solution. This fluid contains water and glucose in concentrations similar to those in blood. These tubes are selectively permeable and allow only certain substances to pass through them. Blood is then passed through the semi-permeable coiled cellophane tubes. The tubes allow small molecules such as urea, creatinine and uric acid to pass out.
Metabolic wastes are also filtered out in the surrounding solution. Macromolecules such as proteins are retained in the blood. Purified blood is then mixed with antiheparin and warmed to the body temperature. The purified blood is returned through a vein in the same arm. The function of dialysis is similar to the function of the kidney, but the only difference is that there is no reabsorption during dialysis.

Breathing in humans is divided into 2 steps:

1. Inhalation: In the process of inspiration, there would be a contraction of muscles attached to the ribs on the outer side which pulls out the ribs and results in the expansion of the chest cavity. Later, the diaphragm, contracts, moves downwards and expands the chest cavity resulting in the contraction of the abdominal muscles. The expansion of the chest cavity produces a partial vacuum which sucks air into the lungs and fills the expanded alveoli.
2. Exhalation: The expiration process is considered once after the gaseous exchange occurs in the lungs and the air is expelled out. This expulsion of air is called expiration. During this process, muscles attached to the ribs contract, the muscles of the diaphragm and the abdomen relax which leads to a decrease in the volume of the chest cavity and increases the pressure of the lungs, causing the air in the lungs to be pushed out through the nose.

1. (i) Organism A is a green plant, (ii) Food B is glucose and (iii) Food H is starch.
2. C is carbon-dioxide and D is water.
3. (i) The green coloured substance E is chlorophy ll and (ii) Organ F is a leaf.
4. The process G is photosynthesis.

A dialysis machine tries to mimic some of the functions of a human kidney. One of the primary work of a kidney is to remove urea and certain salts from the blood so they can exit the body in urine.
In a dialysis machine, blood from the patient runs through tubes made of a semi-porous membrane. Outside the tubes is a sterile solution made up of water, sugars and other components. Red and white blood cells and other important blood components are too large to fit through the pores in the membranes, but urea and salt flow through membranes into the sterile solution. The blood is passed along the tubes placed in dialyzing fluid that filter waste products from the blood through diffusion. The filtered blood is transported back into the body.

Terrestrial Respiration		Aquatic Respiration
1.	Respiration is through lungs.	Respiration is through gills.
2.	Air contains more oxygen so organism will not have to spend more energy.	Diffusion of oxygen is less in water so aquatic organism will have to spend more energy.
3.	occurs in organisam living in the land.	occurs in organisam living in the water.
4.	Terrestrial animals respire by lungs and they have a soft, slippery skin.	Aquatic animals respire by gills and they have a leathery hard or spiny skin.

The diagram of alimentary canal of man and its parts are shown below:

The main difference between single circulatory systems and double circulatory systems is that in the case of single circulatory systems, blood passes through the heart only once on each circuit around the whole of the blood circulation system of the animal.but the double circulatory systems blood is pumped twice. Once from the heart to the lungs and then from heart to rest of the body.
In the single circulation the deoxygenated blood from the whole body of the animal spammed into the heart. From the heart it goes to the gills and the oxygenated blood is pumped back into the body. This kind of circulation takes place in fishes. Conversely, in the case of double circulatory systems, blood passes through the heart twice during one complete circuit around the blood system through the body of the animal. double circulation the deoxygenated blood is collected from the body, goes to the lungs for the process of oxygenation and then this oxygenated blood comes back to the heart. The heart pumps back this oxygenated blood into the body tissues. In this type of circulation, as the blood passes through the heart two times, it is known as double circulation. It takes place in birds & mammals like human beings.

1. Organism B is undergoing aerobic respiration.
2. Organism A is undergoing anaerobic respiration.
3. In anaerobic respiration, glucose breaks down to form alcohol and carbon dioxide with the release of small amount of energy. Hence, organism A can convert glucose into alcohol.
4. Yeast behaves like organism A.
5. Humans and dogs behave like organism B.

The double circulatory system of blood flow refers to the separate systems of pulmonary circulation and the systemic circulation.
The adult human heart consists of two separated pumps, the right side with the right atrium and ventricle which pumps deoxygenated blood into the pulmonary circulation.
The oxygenated blood re-enters the left side of the heart through the pulmonary vein into the left atrium and passes to the left ventricle where it is pumped to the rest of the body. This part of the circulation is called as systemic circulation. This type of circulation is called double circulation. The advantage of a double circulatory system is that blood can be pumped to the rest of the body at a higher pressure.

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:
Factors on which the diffusion depends are:

• TEMPERATURE: With the rise in temperature, the rate of diffusion increases. Because with the rise in temperature, the kinetic energy of diffusing particles also increases.
• DIFFUSION PRESSURE GRADIEN: Greater the diffusion pressure gradient , more will be net diffusion of molecule.
• DENSITY OF DIFFUSING SUBSTANCE: The rate of diffusion is inversely proportional to square of the density of the diffusing substance.
• MEDIUM: More the concentrated medium, slower will be rate of diffusion.

Thevarious methods used by the plants to get rid of their waste products are:

1. The plants get rid of gaseous waste products through stomata in leaves and lenticels in stems.
2. They get rid of solid and liquid waste by shedding off leaves, peeling of bark and falling of fruits.
3. Secreting gums and resins.
4. Plants excrete some waste substances into the soil around them.

In a nephron, ultra-filtration occurs in the renal corpuscle (glomerulus + Bowman’s capsule). Glomerular filtration of blood is also known as ultra filtration. It is a non-selective process and filtration is so fine that every component of plasma (water, glucose, amino acids, urea, etc) except proteins pass into the Bowman’s capsule. The epithelium of renal corpuscle has tiny filtration slits (also called slit pores) that help in ultra-filtration. This process ensures that only waste products and excess water are removed from the body and it also helps to concentrate the urine.

Greeb plants are autotrophs, they do prepere their own food material.
The word 'auto' means 'self' and 'trophe' means 'nutrition'. Thus, autotrophic means 'self-nutrition’. Green plants are able to prepare their own food from simple raw materials like carbon dioxide from the air, water from the soil and energy from the sunlight. This mode of nutrition where green plants make food themselves from simple substances is called autotrophic nutrition. Such plants are therefore called autotrophs.
Since animals lack chlorophyll they are incapable of manufacturing their own food. They have to depend directly or indirectly on plants for food. Animals are thus heterotrophic where ‘hetero’ means different. hich means that they cannot make their own food as plants do

1.  

1. The process by which water and dissolved minerals get into the root hair of a plant is known as diffusion. Hence, A is diffusion.
2. The water and dissolved minerals are absorbed by the cells of the root hair, which enter the conducting tissue known as xylem. Hence, B is xylem.
3. Transpiration helps in transporting water and dissolved minerals to move up through the xylem tissue (B) in the roots and the stem, and reach the leaves of a plant. Hence, C is transpiration.
4. In leaves, the food is prepared by a process known as photosynthesis. Hence, the process D is photosynthesis.
5. The food synthesised by the leaves of a plant is transported to all the parts of a plant through tissue phloem (E). Hence, E is phloem.
6. The process of distributing (or transporting) food made in the leaves to all the parts of the plant is called translocation. Hence, F is translocation.

2. B represents xylem, while E represents phloem. Out of these, phloem (E) is made of living cells.
3. E (phloem) contains sieve tubes.
4. B (xylem) contains tracheids.

1. Organism B refers to an omnivore, Organism D refers to a herbivore and Organism A refers to a carnivore.
2. Organism C is an autotroph.
3. The organisms A, B and D are heterotrophs as they obtain food from other organisms and cannot synthesise their own food.
4. Organism C can be a producer as it is an autotroph.
5. The organisms A, B and D are consumers as they all are heterotrophs.
6. The examples of organisms A, B, C and D are lion, crow, green plants (like mango) and cow, respectively.

Aerobic respiration:

1. Aerobic respiration takes place in the presence of oxygen.
2. Complete breakdown of food occurs in aerobic respiration.
3. The end products in aerobic respiration are carbon-dioxide and water.
4. Aerobic respiration produces a considerable amount of energy.

Example: Human Beings.
Anaerobic respiration:

1. Anaerobic respiration takes place in the absence of oxygen.
2. Partial breakdown of food occurs in anaerobic respiration.
3. The end products in anaerobic respiration are ethanol and carbon-dioxide (in yeast) and lactic acid (in animal muscles).
4. Much less energy is produced in anaerobic respiration.

Example: Yeast.

	Autotroph	Heterotroph
1.	Food: It manufactures its own food.	It obtains its food from outside source.
2.	Chlorophyll: It has chlorophyll for performing photosynthesis.	Chlorophyll is absent.
3.	Energy: It is obtained from sunlight and changed into chemical energy.	It does not require an external source of energy as the same is present in food obtained from outside.
4.	Digestion: It is absent.	Food obtained from outside is digested before being absorbed and assimilated.

Human heart has four chambers that is two auricles and two ventricles. Auricles are the small chambers whereas ventricles are the bigger ones. Presence of four chambered heart serves two purposes. First, it ensures complete segregation of oxygenated and deoxygenated blood. Second, blood is received by the upper chambers and is pumped out by the lower chambers. This segregation between received blood and sent blood increases the efficiency of the heart.

1. Organ A is kidney. Complete damage of the kidney (organ A) can lead to the accumulation of waste material B, i.e. urea, in the blood.
2. The waste substance B is urea.
3. (i) In dialysis, the blood from a convenient artery is pumped into the dialyser of a dialysing machine. The dialyser contains a coiled cellophane tube made of substance E, called cellulose. It is surrounded by the dialysing solution (F). Hence, E represents cellulose. (ii) F represents the dialysing solution.
4. The dialysing solution contains water (G), glucose (H) and salts (I), which is similar in concentration to those in normal blood.
5. The process of removing waste substances like urea from the blood using a kidney machine is known as dialysis.

The small intestine is the site of the complete digestion of carbohydrates, proteins and fats. It receives the secretions of the liver and pancreas for this purpose. The food coming from the stomach is acidic and has to be made alkaline for the pancreatic enzymes to act. Bile juice from the liver accomplishes this in addition to acting on fats. Fats are present in the intestine in the form of large globules, which make it difficult for enzymes to act on them. Bile salts break them down into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic juice, which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats. The walls of the small intestine contain glands, which secrete intestinal juice. The enzymes present in it finally convert the proteins to amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol.

There are mainly two modes of nutrition:
Autotrophic: Autotrophic nutrition is that mode of nutrition in which an organism makes its own food from the simple inorganic materials like carbon-dioxide and water present in the surroundings (with the help of sunlight energy).
Example: Green plants obtain food by autotrophic nutrition.
Heterotrophic: Heterotrophic nutrition is that mode of nutrition in which an organism cannot make its own food from simple inorganic materials like carbon-dioxide and water, and depends on other organisms for its food.
Example: All animals obtain food by heterotrophic nutrition.

1.  

1. Organism A has parasitic mode of nutrition.
2. Organism B has holozoic mode of nutrition.
3. Organism C has saprophytic mode of nutrition.

2. The organisms like D are called hosts.
3. The process E is egestion.
4. The example of organisms like

1. A is Cuscuta.
2. B is cow.
3. C is mushroom.

5. The general name of the three modes of nutrition exhibited by organism A, B and C are parasitic nutrition, holozoic nutrition and saprophytic nutrition, respectively.

1. Lymph (X) is a light yellow colour (Y) liquid that circulates in the human body. It circulates from the body tissues to the heart. Hence, (i) the liquid X is lymph., (ii) The colour Y is light yellow.
2. The liquid X (lymph) is cleaned of germs and dead cells by a special type of white blood cells called lymphocytes (Z). Lymphocyte helps in fighting infections and diseases. Thus, Z represents lymphocytes.
3. The liquid X, i.e. lymph, is somewhat similar to plasma.
4. The liquid X, i.e. lymph, is not red because it does not contain red blood cells that have red colour pigment called haemoglobin.

Plants utilise Oxygen both during day as well as night for respiration. During the day the plants photosynthesise. In photosynthesis process plants use Carbon dioxide from the atmosphere. Oxygen is a byproduct of photosynthesis. Plants don't need so much oxygen for respiration.
They use some of it and release the remaining which animals use for their respiration. So you can say that plants take in carbon dioxide and give out oxygen during the day. At night plants cannot do photosynthesis because there is no light. But they continue to respire for which they take in oxygen and give out carbon dioxide however Oxygen produced during photosynthesis is much more than that utilised during respiration so over all plants give more Oxygen than they consume.

Peristaltic movement is the type of movement in which there is the constriction and relaxation of muscles of the esophagus, intestine, and stomach. It is a wave-like structure, which starts in the esophagus when the bolus of food is swallowed.
The contraction and relaxation of the muscles during the peristaltic movement help in bringing down the food with the food pipe into the stomach. It is an important and automatic process which help in movement of food.

Each nephron is a cluster of very thin-walled blood capillaries. Each capillary cluster in the kidney called glomerulus is associated with the cup shaped Bowman's capsule that collects the filtered urine. Nephron filters the blood in order to remove nitrogenous waste. They also absorb some useful substance such as glucose, amino acids, minerals and major amount of water from filtrate.

Aerobic respiration produces more energy as in it completely the glucose is completely break down into its subsequent particles by which it is made up of and the full amount of the energy stored in it is received in the form of ATP to our body cells but in anaerobic respiration the complete break down of glucose is not done. the process of aerobic respiration as many as 36 molecules of ATP are produced for every molecule of glucose that is utilized. This shows that aerobic respiration produce much more energy than anaerobic respiration, which produces only 2 ATP molecules.

1. W is the dental plaque.
2.  

1. X refers to the saliva.
2. Y refers to the salivary glands.

3. Organisms Z are bacteria.
4. Layer of W, i.e. dental plaque, can be removed by regular brushing of teeth.

Lymphatic system: A system of tiny tubes called lymph vessels (lymphatics) and lymph nodes (lymph glands) in the human body which transports the liquid called lymph from the body tissues to the blood circulatory system is called lymphatic system. Functions of lymphatic system:

1. It takes part in the nutritive process of the body.
2. It protects the body by killing the germs drained out of the body tissues with the help of lymphocytes contained in the lymph nodes, by making antibodies.
3. It helps in removing the waste products like fragments of dead cells etc.

Functions of blood are as follows:

• It supplies oxygen to cells and tissues.
• It supplies essential nutrients to cells, such as amino acids, fatty acids, and glucose.
• It removes carbon dioxide, urea and lactic acid (waste products)
• Its white blood cells have antibodies which defend us from infection and foreign bodies.
• It has specialized cells, such as platelets, which help the blood to clot (coagulate) when we are bleeding.
• It transports hormones-chemicals released by a cell in one part of the body that sends out messages that affect cells elsewhere in the body.
• It regulates our acidity (pH) levels.
• It regulates our body temperature. When the weather is very warm or during strenuous exercise there will be increased blood flow to the surface, resulting in warmer skin and faster heat loss. When environmental temperatures drop, blood flow focuses more on the important organs deep inside the body.

The main components of blood are:

1. Plasma: It carries all the dissolved substances such as proteins, digested food, common salt etc from one part to another part of the body.
2. Red blood corpuscles (RBC): It carries oxygen from the lungs to all the cells of the body.
3. White blood corpuscles (WBC): It fights infection and protects us from diseases.
4. Platelets: It helps in the coagulation of blood in a cut or wound.

• Each and every respiration organ is designed by the nature in a specialised way. This all is done in order to maximise its functional capability.
• For e.g.- Nostrils have mucous lining and hair so that it can prevent entry of harmful bacteria in the body.
• Trachea gets divided into bronchi & bronchioles to supply air to each & every part of lungs.
• Lungs have numerous sac like structure called as alveoli which increases the surface area of lungs so that better exchange of gases can take place.
• Each and every respiration organ is designed by the nature in a specialised way. This all is done in order to maximise its functional capability.
• For e.g.- Nostrils have mucous lining and hair so that it can prevent entry of harmful bacteria in the body.
• Trachea gets divided into bronchi & bronchioles to supply air to each & every part of lungs.
• Lungs have numerous sac like structure called as alveoli which increases the surface area of lungs so that better exchange of gases can take place.
• Alveoli are very thin walled in order to promote better and easier diffusion of gases.