BIOLOGY VST-IV

Complete the following flow chart.

Answer explanation

(A) Hydrochloric acid

(B) Pepsin

(C) Mucus

(D) Functions of hydrochloric acid:

(i) HCl makes the medium acidic as protein digesting enzymes pepsin acts in acidic medium. (ii) It kills the harmful bacteria present in the stomach. (E) Function of pepsin: Pepsin breaks down proteins into peptones. (F) Function of mucus: Mucus protects the inner lining of the stomach from the action of the acid under normal conditions. Explanation: Gastric glands present in the wall of stomach secrete gastric juice. Gastric juice comprises these three secretions: HCl, pepsin and mucus. Gastric juice also contains gastric lipase which partially breaks down lipids.

Tags

NGSS.MS-LS1-2

NGSS.MS-LS1-3

Respiratory structures of two diferent animals– a fish and a human being are as shown.Observe (a) and (b) and select one charac teristic that holds true for both of them.

• (a) Both are placed internally in the body of animal.

• (b) Both have thin and moist surface for gaseous exchange.

• (c) Both are poorly supplied with blood vessels to conserve energy.

• (d) In both, the blood returns to the heart after being oxygenated.

Answer explanation

Explanation: The surface from where the gaseous exchange (oxygen and carbon dioxide) takes place with the surrounding is called respiratory surface. The features of respiratory surface are: (i) (ii) It is extremely thin and moist It has a large surface area (iii) It is richly supplied with blood capillaries. (iv) It is permeable to gases.

Tags

NGSS.MS-LS4-2

List four functions of the human heart. Why is double circulation necessary in the human body?

Answer explanation

Functions of the human heart are as following:

(1) The human heart is a muscular organ that pumps oxygenated blood throughout the body.

(2) It controls heart rate

(3) It maintains blood pressure

(4) It pumps hormones and other vital substances to diferent parts of the body. Double circulation is necessary as the separation of oxygenated and deoxygenated blood allows a more efficient supply of oxygen to the body cells as mammals have high energy needs.

(A) Identify any two parts from the above diagram which carry oxygenated and deoxygenated blood.

(B) Explain the process of double circulation with the help of a low chart.

Answer explanation

(A) Oxygenated : B/D/F [B = left ventricle/D = aorta/F = left auricle/ pulmonary vein] Deoxygenated: A/C/E [A = right ventricle/C = pulmonary artery/E = right auricle/vena cava] (any two)

A student sets up an experiment to study the photosynthesis in plants. The student destarched a potted plant by keeping it in a dark room for 3 days. Half of the portion of destarched leaf was placed in a bottle containing caustic potash (absorbs CO2) as shown.The student then places the plant in light and tests the leaf after 5 hours for the presence of starch. The portions inside the bottle shows negative starch test by relecting no change in colour when react with iodine, however, other upper portions of the leaf gave positive starch test showing blue-black colour with iodine. What can be evaluated from this experiment?

(a) Carbon dioxide is directly linked with the colour of leaf. (b) Carbon dioxide is necessary for preparing carbohydrate. (c) Lack of carbon dioxide increases amount of starch in plant. (d) Lack of carbon dioxide slows the process of photosynthesis.

Answer explanation

(b) Carbon dioxide is necessary for preparing carbohydrate Explanation: When the student places the plant in light for 5 hours, The portion of leaf outside the bottle prepared food by the process of photosynthesis. Whereas the portion of leaf inside the bottle having NaOH did not prepare any food. The portion of leaf which was outside the bottle having NaOH showed the positive test with iodine solution as that portion has made starch in ive hours by taking carbon dioxide from the atmosphere so this activity suggests that CO2 is necessary for the process of photosynthesis

Tags

NGSS.MS-LS1-6

NGSS.MS-LS2-1

The given igure represents a common type of dialysis called Haemodialysis. It removes waste products from the blood. Such as excess salts, and urea which are insufficiently removed by the kidney in patients with kidney failure. During the procedure, the patient’s blood is cleaned by iltration through a series of semi-permeable membranes before being returned to the blood of the patient. On the basis of this, answer the following questions:

Questions:

(A) (i) Name the iltering units present in the human kidneys. (ii) Name the main excreting waste removed by kidneys from blood?

(B) What are the two main functions of kidneys?

(C) What are the major factors on which the amount of water reabsorbed in the part of nephron depends?

A.(I)Identify the structure labelled A,B,C &D

(II)(ii) Explain how the structure A is adapted to perform photo synthesis.

(B) Write the pathway taken by a molecule of carbon dioxide from the atmosphere to the site of phtosynthesis.

(C)(i)What type of reaction is photosynthesis.

(ii)Write down the balanced symbol equation for photosynthesis.

(iii) Explain how the two reactants in photosynthesis become available in the leaves of plants.

Tags

NGSS.MS-LS1-6

NGSS.MS-LS2-3