Chapterwise important questions life process

Chapterwise important questions life process

sms (smart studies ) November 22, 2020

 

NCERT Hindi Book explanation in English and tamil 

NCERT solutions Hindi सूरदास


Life process

Multiple  Choice  Questions

1.If  salivary  amylase  is  lacking  in  the  saliva, which  of  the  following  events  in  the  mouth cavity will be affected?
 

(a)Proteins breaking down into amino acids

(b)Starch breaking down into sugars

(c)Cats breaking down into fatty acids and glycerol

(d)Absorption of vitamins [CBSE 2010]

Ans.(b)Starch breaking down into sugars

Explanation: 

1.The process of digestion begins in the mouth. The mouth contains a digestive enzyme, salivary amylase. This enzyme breaks the starch molecules in the food, into maltose. 

2.The  absence  of  amylase  in  the  saliva  thus affects the breakdown of starch into simpler sugar molecules. The  food  then  passes  from  oesophagus  to stomach  where  the  protein  digestion  takes place  by  the  enzyme,  pepsin.  

3.Pepsin  breaks down the protein into amino acids. The fats are broken down into small particles by bile in the small intestine and then broken down into fatty acids and glycerol by lipases present in pancreatic ʼnuice.Absorption of vitamins takes place in the small intestine.

Related Theory:  In the mouth, salivary glands secrete saliva. Saliva is a watery fluid which contains an enzyme called salivary amylase, which partially digests the starch and converts it into maltose sugar.

2.In  the  excretory  system  of  human  beings, some  substances  in  the  initial  filtrate  such as glucose, amino acids, salts and water are selectively reabsorbed in:

(a)Urethra

(b) Nephron

(c)Ureter

(d)Urinary bladder [CBSE 2020]

Ans.(b) Nephron.

Explanation: A nephron is a filtering unit present in kidney. It has different parts like Bowman’s capsule, glomerulus and tubular region (Renal tubule).  Glucose,  amino  acids  and  salts  are selectively reabsorbed in tubular region.

1. Urine is released periodically to the exterior through urethra.

2. Urine formed in the kidneys passes down the ureters to the urinary bladder.

3. Urine is stored in the urinary bladder till it is excreted outside.

 

3.Which part of alimentary canal receives bile from the liver?

(a)Stomach

(b)Small intestine

(c)Large intestine

(d) Oesophagus [CBSE 2010]

Ans.(b) Small intestine

Explanation: Bile is secreted by the liver and is stored in the gall bladder from where it enters the small intestine via a common duct.

Related Theory :It performs two functions:

•makes the food alkaline.

•breaks the fats present in food into small globules by the process of emulsification.

4.Pseudopodia are:

(a)small  hair-like  structures  present  on unicellular organisms.

(b)false feet developed in some unicellular organisms.

(c)long,  tube-like  structures  coming  out  of the mouth.

(d)suckers which are attached to the walls of the intestines. glomerulus and tubular region   (Renal   tubule).   Glucose,   amino acids and salts are selectively reabsorbed in tabular region. [CBSE 2020]

Ans.(b)false  feet  developed  in  some  unicellular organisms.

Explanation:  Pseudopodia  are  developed  in amoeba. Amoeba engulfs its food particles by forming pseudopodia around it. The food particle gets  surrounded  by  encircling  pseudopodia’s tips.  At  this  point  the  cell  membrane  closer to food particle gets dissolved and the food is captured into the cell. The process of ingestion in amoeba is called phagocytosis.

Related Theory : Pseudopodia also helps in locomotion.

5.A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that the rice water contains:

(a)Complex proteins

(b)Simple proteins

(c)Cats

(d)Starch[NCERT]

Ans.(d)Starch

Explanation:  Iodine  solution  is  often  used for testing the presence of starch in the food particles. When iodine is added to starch, it turns blue-black. Rice water contains starch, hence when iodine solution is added to rice water it turns blue-black.

6.Which  one  of  the  following  statements  is correct about the human circulatory system?

(a)Blood  transports  only  oxygen  and  not carbon dioxide.

(b)Human heart has five chambers. 

(c)Valves  ensure  that  the  blood  does  not flow backwards.

(d)Both  oxygen-rich  and  oxygen-deficient blood gets mixed in the heart.[CBSE 2020]

Ans.(c)Valves ensure that the blood does not flow backwards.

Explanation:  One  of  the  functions  of  blood is  transport oxygen, carbon dioxide, enzymes, hormones etc. from one part of body to another so this statement:

(1)is incorrect.

(2)Human heart has four chambers— 2 Atria and 2 ventricles so statement (B) is incorrect.

(3)Both  oxygen–rich  and  oxygen-deficient blood  does  not  get  mixed  in  the  human heart  as  it  has  four  chambers.  The  left side chamber-left atrium and left ventricle carry  only  oxygenated  blood.  Whereas right atrium and right ventricle have only de-oxygenated blood and they do not get mixed in the process of circulation. Hence, this statement is incorrect.

(4)Valves  prevent  backward  flow  of  blood as  they  are  located  at  each  end  of  two ventricles and act as one way inlet.

Related Theory 

Our heart has 4 values. 

Tricuspid  valves:  Present  between  right  atrium  and right ventricle. 

Pulmonary  valve: Present  between  right  ventricle and the pulmonary artery. 

Mitral valve: Present between the left atrium and the left ventricle. 

Aortic  value:  Present  between  left  ventricle  and aorta.

7.Choose the function of the pancreatic ʼnuice from the following:

(a)Trypsin  digests  proteins  and  lipase carbohydrates

(b)Trypsin digests emulsified fats and lipase proteins

(c)Trypsin and lipase digest fats

(d)Trypsin digests proteins and lipase digests emulsified fats droplets[CBSE 2014]

Ans.(d)Trypsin  digests  proteins  and  lipase  digests emulsified fats droplets.

Explanation: Pancreas secretes pancreatic ʼnuice which contains trypsin, lipase and pancreatic amylase.  Trypsin  digests  the  proteins,  lipase breaks down the fat droplets already emulsified by  bile  salts  and  pancreatic  amylase  breaks down the starch.

8.Anaerobic process:

(a)takes place in yeast during fermentation.

(b)takes place in the presence of oxygen.

(c)produces only energy in the muscles of human beings.

(d)produces ethanol, oxygen and energy.[CBSE 2020]

Ans.(a)takes place in yeast during fermentation.

9.When air is blown from mouth into a test tube containing  lime  water,  the  lime  water  turns milky due to the presence of:

(a)Oxygen

(b)Carbon dioxide

(c)Nitrogen

(d)Water vapour[NCERT]

Ans.(b)Carbon dioxide.

Explanation:  The  lime  water  turns  milky on passing carbon dioxide gas into it  due to formation of insoluble calcium carbonate. When the exhaled air rich in carbon dioxide is blown from mouth into test tube, it reacts with lime water (calcium hydroxide) to produce calcium carbonate and water. The reaction is:

 

10.most of the digestion and absorption of the food takes place in the: 

(a)small intestine 

(b)liver 

(c)stomach 

(d)large intestine[CBSE 2020] 

Ans.(a)small intestine. 

Explanation: Small intestine receives juices from liver, pancreas and walls of small intestine.Bile juice from liver emulsifies the fats and makes the medium alkaline. Pancreas and small intestine juices contain amylase, lipase and tryspin.

 

This completes the digestion of food. The inner lining of small intestine has numerous villi; (finger-like proʼnections) which increase the surface area for absorption of food.The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body, where it is utilized for getting energy for the body, building up new tissues and repairing old tissues.Large intestine: Water is absorbed from the undigested food and it changes to semi-solid faeces and is stored in the rectum till it is egested out through anal opening by the activity of anal sphincter.

11.Which of the following statement (s) is (are) true about respiration? 

(i) During inhalation, ribs move inward and diaphragm is raised.

 (ii) In the alveoli, exchange of gases takes place i.e. oxygen form alveolar air diffuses into blood and carbon dioxide from blood into alveolar air.

 (iii) Haemoglobin has greater aǝinityf or

 (a)(i) and (iv)

 (b)(ii) and (iii) 

(c)(i) and (iii) 

(d)(ii) and (iv)

Ans.(d)(ii) and (iv).

 

Explanation: During inhalation, the ribs move out and the diaphragm flattens. As a result, the surface area for gaseous exchange increases. The site for gaseous exchange in the lungs are alveoli. The alveoli increases the surface area.

for gaseous exchange in the lungs. The blood from different parts of the body, rich in carbon dioxide reaches the alveoli through the blood vessels. The oxygen from the alveoli is diffused into the blood. 

 On the other hand, the carbon dioxide from the blood is diffused to the alveoli. The oxygen rich blood is then supplied to the different cells in the body. 

The haemoglobin present in the blood, is the respiratory pigment. It has a much greater affinity for oxygen than for carbon dioxide. Due to this, oxygen molecules bind to haemoglobin present in the red blood corpuscles and are transported to all parts of the body with the help of cells.

12.In which part of the alimentary canal food is finally digested? 

(a)Stomach 

(b)Mouth cavity 

(c)Large intestine 

(d)Small intestine 

Ans.(d)Small intestine 

Explanation:Digestion of food starts in mouth by salivary amylase. From here it enters into the stomach via oesophagus. Gastric ʼnuice of stomach digests the protein part of food. Pancreatic amylase, trypsin and lipase as well as intestinal peptidases and maltase carry out the final chemical digestion of food in small intestine. The simpler substances formed by chemical digestion are then absorbed by small intestinal villi. 

13.Which is the correct sequence of air passage during inhalation? 

(a)Nostrils → Larynx → Pharynx → Trachea → Lungs 

(b)Nasal passage → Trachea → Pharynx →Larynx → Alveoli 

(c)Larynx → Nostrils → Pharynx → Lungs 

(d)Nostrils → Pharynx → Larynx → Trachea → Alveoli [CBSE 2013]

Ans. (d)Nostrils → Pharynx → Larynx → Trachea → Alveoli 

Explanation: During inhalation, the air is drawn through the nostrils into the nasal passage. From there, air enters into pharynx, larynx, trachea (windpipe), bronchi, lungs and finally to the alveoli. 

14.If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected? 

(a)Proteins breaking down into amino acids

(b)Starch breaking down into sugars

(c)Cats breaking down into fatty acids and glycerol

(d)Absorption of vitamins 

Ans.(b)Starch breaking down into sugars.

Explanation:Amylase is the enzyme which helps in primary digestion of starch only. Digestion of starch by salivary amylase into maltose starts in mouth. Oesophagus then pushes the food into stomach. It does not carry out digestion at all. Pancreatic amylase also digests remaining starch into maltose sugars. Intestinal maltase carries out final chemical digestion of maltose into glucose molecules. 

15.During respiration, the exchange of gases take place in: 

(a)Trachea and larynx

 (b)Alveoli of lungs 

(c)Alveoli and throat

 (d)Throat and larynx [CBSE 2010, 13] 

Ans.(b)Alveoli of lungs 

Explanation: The site for gaseous exchange in the lungs is the alveoli. They are tiny balloon-like structure that increase the surface area for gaseous exchange in the lungs. The alveoli have very thin walls and are richly supplied with blood vessels surrounding them. These blood vessels bring carbon dioxide rich blood from different parts of the body to the alveoli. The alveoli on the other hand receives oxygen from the surroundings. The carbon dioxide from the blood vessels diffuse into the alveoli while the oxygen from the alveoli diffuses into the blood vessels. As a result, gaseous exchange takes place between alveoli and blood vessels. 

16.Which of the following statement(s) is/are true about heart?

 (i)Left atrium receives oxygenated blood from different parts of body while right atrium receives de-oxygenated blood from lungs

 (ii)Left ventricle pumps oxygenated blood to different body parts while right ventricle pumps de-oxygenated blood to lungs

 (iii)Left atrium transfers oxygenated blood to right ventricle which sends it to different body parts

 (iv)Right atrium receives de-oxygenated blood from different parts of the body while left ventricle pumps oxygenated blood to different parts of the body 

(a)(i)

(b)(ii) 

(c)(ii) and (iv) 

(d)(i) and (iii) 

Ans.(c)(ii) and (iv) 

Explanation:The left ventricle pumps blood into the aorta which in turn delivers it to the maʼnor body regions and organs which makes statement (c) incorrect 

The anterior vena cava collects deoxygenated blood from the head, chest, and arms and enters the right atrium while the inferior vena cava collects blood from the lower body regions. 

Both venae cavae pass the deoxygenated blood to the right atrium which makes statement  

(i) incorrect. Blood from right atrium enters right ventricle and pulmonary arteries carry deoxygenated blood from right ventricle to lungs for oxygenation; this makes statements  (ii) and (iv) correct. 

17.Single circulation i.e., bl ood flows through the heart only once during one cycle of passage through the body, is exhibited by: 

(a)Labeo, Chameleon, Sa lamander

 (b)Hippocampus, Exocoetus, Anabas 

(c)Hyla, Rana, Draco 

(d)Whale, Dolphin, Turtle [NCERT] 

Ans.(d)Whale, Dolphin, Turtle 

Explanation: The examples and the relation of animal group and heart are as follows: 

  

Related Theory :Fishes have two-chambered heart and exhibit single circulation, while three-chambered heart of amphibians and reptiles and four-chambered heart of birds and mammals exhibit double circulation.

 

 18.Single circulation, i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by:

 (a)Labeo, Chameleon, Salamander

 (b)Hippocampus, Exocoetus, Anabas

 (c)Hyla, Rana, Draco

 (d)whale, dolphin, turtle 

Ans.(b)Hippocampus, Exocoetus, Anabas 

 Explanation: The examples and the relation of animal group and heart are as Fishes have two chambered heart and exhibit single circulation while three chambered heart of amphibian and reptiles and four chambered heart of birds and mammals exhibit double circulation. In given options, b includes all fishes which makes it correct answer.

 19.In which of the following vertebrate group/groups, does heart not pump oxygenated blood to different parts of the body? 

(a)Pisces and amphibians 

(b)Amphibians and reptiles

 (c)Amphibians only 

(d)Pisces only[NCERT]

 Ans.(d)Pisces only

 Explanation: Fishes have only two chambers to their hearts, and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body. Fishes take in water through their mouths and force it past the gills where the dissolved oxygen is taken up by blood. 

20.Which of the following statements about the autotrophs is incorrect:

(a)They synthesize carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll 

(b)They store carbohydrates in the form of starch 

(c)They convert carbon dioxide and water into carbohydrates in the absence of sunlight

 (d)They constitute the first trophic level in food chains 

Ans.(c)They convert carbon dioxide and water into carbohydrates in the absence of sunlight 

Explanation:Autotrophs obtain the required carbon and energy requirements from carbondioxide and Sunlight. They combine carbon dioxide and water to form carbohydrates. 

Themain photosynthetic pigment is chlorophyll, which helps to trap the Sunlight to carry out thelight reaction of photosynthesis to synthesise carbohydrates. 

Since autotrophs are the only organisms that can fix the atmospheric carbon dioxide intoorganic compounds, these organisms occupy first trophic level in food chain and serve as asource of food and energy for organisms of higher trophic levels. 

21.Oxygen liberated during photosynthesis comes from: 

(a)Water

(b)Chlorophyll

(c)Carbon dioxide 

(d)Glucose [CBSE 2010] 

Ans.(a)Water 

Explanation: The oxygen during photo-synthesis comes from split water. Concept Applied 

Steps of photosynthesis are as follows:

(i)Absorption of light energy by chlorophyll. 

(ii)Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. 

(iii)Reduction of carbon dioxide to carbohydrates.6CO2 + 6H2O Chlorophyll→ Sunlight C6H12O6 + 6O2 Glucose 

22.In the list of organisms given below, those that reproduce by the asexual method are: 

(i)Banana 

(ii)Dog 

(iii)Yeast 

(iv)Amoeba 

(a)(ii) and (iv)

(b)(i), (iii) and (iv)

(c)(i) and (iv) 

(d)(ii), (iii) and (iv)

 Ans.(b)(i), (iii) and (iv)

 Explanation:Among the given options, Amoeba (binary fission), Yeast (budding) and banana (vegetative propagation) reproduce by asexual reproduction whereas dogs reproduce by sexual method.Related Theory¬In asexual reproduction, only one parent is involved, no garmetes are produced, no fertilization takes places and all the offsprings are exact copy of their parents.

 23.The blood leaving the tissues becomes richer in: 

(a)Carbon dioxide 

(b)Water

 (c)Haemoglobin 

(d)Oxygen[NCERT] 

Ans.(a)Carbon dioxide

NCERT Hindi Book explanation in English and tamil 

NCERT solutions Hindi सूरदास


 

 

 

 

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