Wednesday, 25 April 2012

Class 10 - Biology - CH6 - Life Processes (#cbsenotes)

Life Processes

MCQs, NCERT Chapter Solutions and other Q & A

See Quiz Life Processes

Q1. The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.

Answer: (c) excretion.

Q2. The xylem in plants is responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.

Answer: (a) transport of water.

Q3. The autotrophic mode of nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.

Answer: (d) All of the above

Q4. The breakdown of pyruvate to give carbon dioxide, water and energy take place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.

Answer: (b) mitochondria

Q5. Movement of food through oesophagus is due to

(a) Lubrication by saliva
(b) Peristalsis
(c) Gravitational Pull
(d) All of the above

Answer: (b) Peristalsis

Q6. Where is bile produced?

(a) Gallbladder
(b) Blood
(c) Liver
(d) Spleen

Answer: (c) Liver

Q7: In normal expiration, the diaphragm is
(a) Arched
(b) Flattened
(c) Perforated
(d) None of these

Answer: (a) Arched

Q8: The correct pathway of blood in the circulatory system is
(a) atria → ventricles → arteries → veins
(b) ventricles → atria → veins → arteries
(c) ventricles → veins → arteries → atria
(d) veins → ventricles → atria → arteries

Answer: (a)

Q9: Respiration is a process in which 
(a) Energy is stored in the form of ADP
(b) Energy is released and stored in the form of ATP
(c) Energy is used up
(d) Energy is not released at all.

Answer: (b) Energy is released and stored in the form of ATP

Q10: Name an organ which is part of two body systems.

Answer: Pancreas which if part of
  • Endocrine System
  • Digestive System

Q11:  Why do raw bread taste sweeter on mastication?

Answer: It is because salivary glands secrete Salivary Amylase which converts starch into sugars.

Q12: How are fats digested in our bodies? Where does this process take place? 

Answer: The small intestine is the site of the complete digestion of fats. Fats are present in the intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile juice from the liver accomplishes this. Bile salts emulsify these large globules of fats and 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 fats into fatty acids and glycerol.

Q13: What is the role of saliva in the digestion of food? 

Answer: Saliva is a fluid which is secreted by the salivary glands. It helps in digestion of food by following ways:
  1. Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into sugars (maltose).
  2. It cleans the mouth cavity and tends to destroy germs that cause teeth decay. It contains lysozymes which help in destroying the bacteria.
  3. It moistens and lubricates food which again helps in swallowing.
  4. It acts as a solvent, dissolving some food particles to stimulate taste buds of the tongue.

Q14: Why will simple diffusion not meet the requirement of human beings?

Answer:  All cells of the body are not in direct contact with the environment. In humans the energy requirements are high. Waste produced is more due to active metabolism. Therefore simple diffusion does not meet the oxygen requirement of human beings.

Q15: What criteria do we use to decide whether something is alive? 

Answer: Following criteria may be used to define whether something is alive:
  1. It is an organised system of molecules that capture energy and nutrients to grow by molecular movements,
  2. It has the ability to reproduce at some point in its lifecycle, and
  3. It has the potential to evolve in response to changes in the environment.

Q16: After long-running, you may experience cramps in your leg muscles. Whats the reason behind this?
Answer: It is due to a sudden build-up of lactic acid (because of lack of oxygen) in our muscles after long exercise. It causes muscular cramps in our leg muscles.

Q17: What processes would you consider essential for maintaining life? 

Answer: Various life processes are essential for maintaining life. Some are:
  • Nutrition
  • Respiration
  • Excretion
  • Transportation

Q18: How do villi enhance absorption of food in the intestine?

  • Increased surface area
  • Highly vascular

Q19: Why bile juice is considered important even though it does not contain any digestive enzymes?

Answer: Bile juice is important for the following reasons:
  1. It contains bile salts and bile pigments that emulsify fats.
  2. Contains NaHCO3 that neutralises the acidic medium of the food in the small intestine.

Q20:  Which organs secrete the following enzymes:
(i) Trypsin
(ii) Pepsin

Answer: (i) Trypsin - Pancreas     (ii) Pepsin - Gastric lining of Stomach

Q21: Name the factors that affect photosynthesis.

  • Light Intensity, its quality and duration.
  • Temperature
  • Water Availability
  • CO2 and O2  availability
  • Other Factors like age and histology of leaf,  amount of chlorophyll present

Q22: Name the vestigial part of a human alimentary canal?

Answer: vermiform appendix or caecal

Q23: What is the name given to rhythmic wave-like manner occurring in alimentary canal?

Answer: Peristalsis or Peristaltic movements

Q24: The bark of woody plants is dead but the inner layers inside the bark are living. How do they get oxygen and release carbon dioxide?

Answer: Through lenticels

Q25: What are lenticels? 

Answer: Lenticels are portions of the periderm (bark) with numerous intercellular spaces. Their purpose is to allow gas exchange through the compactly arranged cork cells of the bark, which otherwise presents an impermeable barrier to the passage of water and gases.

Q26: How does photosynthesis occur?

Answer: The process of photosynthesis is completed in two steps:
  1. light reaction
  2. dark reaction
i) Light reaction: The first step of photosynthesis occurs in the presence of light. During this step, chlorophyll contained in the chloroplast of plant cells absorbs light energy. This energy is converted into another form, which can be supplied for the completion of the dark reaction.

ii) Dark reaction: This second step of photosynthesis does not require light, and is called dark reaction. It can also carry on in the presence of light. During this step, energy generated during the light reaction is used to combine carbon dioxide and water molecules to form energy-rich compounds, such as glucose. Oxygen is also released in this process.

The following equation summarises the raw materials and products of photosynthetic process:

    RAW MATERIALS                               PRODUCTS
    6CO2   + 12H2O    ---------------->  C6H12O6 + 6H2O + 6O2
    carbon      water         chlorophyll     glucose   water  oxygen

Q27: Name the mode of nutrition in an organism that uses simple substances like CO2 and water to prepare food inside its body?

Answer: Autotrophic mode of nutrition.

Q28: What are the differences between autotrophic nutrition and heterotrophic nutrition?


1Green plants are self-dependent because they
synthesise their own food materials by photosynthesis. Such mode of nutrition is
described as autotrophic nutrition.
Organisms which depend upon plants or other organisms for their nutrition.
2Green Plants (producers) are autotrophs.Non-Green Plants, Animals, Parasites are heterotroph (consumers).

Q29: Read following statements from A to E and identify the relevant life process from the following word list.
         growth, transport, synthesis, regulation, nutrition

 A. A butterfly sucking the nectar from the flowers in a garden.
 B. A boy shouts with excitement when his school team wins the match on the last ball.
 C. After finishing lunch, Mohan's blood distributes the food molecules to different cells of his body.
 D. Green plants prepares starch (complex substance) from simpler chemicals.
 E. Radha finds her height has increased by 4 cm since her last birthday.

B- regulation
C- transport
D- synthesis
E- growth

Q30: What is osmoregulation? 

Answer: The regulation of the water content of the cell is called osmoregulation.

Q31: What are the different ways in which glucose is oxidised to provide energy in various organisms?

Answer: Breaking down of glucose involves a two-step process. In the first step, it is broken into three carbon molecule called pyruvate. The pyruvate is further broken down into energy in following different ways in various organisms:
  1. Aerobic Respiration: In this case, pyruvate is broken down into water and carbon dioxide along with the release of energy. It commonly occurs in mitochondria of cells.
  2. Anaerobic Respiration in Yeast: In yeast cells during fermentation pyruvate is converted into ethanol and carbon dioxide in the absence of oxygen.
  3. Anaerobic Respiration in Muscles: Due to lack of oxygen, e.g. during vigorous running or exercise, in human muscles, pyruvate is converted into lactic acid.

Q31: Which organ of the plant body helps in osmoregulation?

Answer: Leaves

Q32: Which organelle of the cell in animals helps in osmoregulation? 

Answer: Contractile Vacuole.

Q33: If kidney fails to reabsorb water, the tissues would
(a) remain unaffected
(b) shrink to shrivel
(c) absorb water from the blood
(d) take more oxygen from the blood

Answer: (c) absorb water from the blood. This condition is called Oedema or Dropsy

Q34: How does transpiration pull help in the ascent of sap?

Answer: Water column builds up as a result of cohesion and adhesion forces. The negative pressure in the upper tissues results in an upward pull of water.

Q35: In what form excretion takes place in plants?

Answer: Plants produce secondary metabolites like organic acids, tannin, resins, latex, gums etc.

Q36(NCERT): What are the components of the transport system in highly organised plants?

Answer: The transport system of organised plants consists of xylem and phloem. Xylem which has vessels and tracheids which transport water and minerals from root to other parts of the plant. Phloem which consists of sieve tubes, sieve cells and companion cells transport food from leaves to storage organs and other parts of the plant. In xylem, the transport is unidirectional i.e. from root upward while in phloem, it is bidirectional.

Q37: What is meant by double circulation? Mention its advantages.

Answer: In human beings and other vertebrates, the blood goes through heart twice during each cycle. This process is known as double circulation. Deoxygenated blood enters through right auricle and then it enters right ventricle from where it is pumped to lungs for oxygenation. From lungs after oxygenation, it comes to left auricle and enters left ventricle from where it is pumped to various parts of the body.

  1. It helps in keeping oxygenated and De-oxygenated blood completely separated.
  2. It increases the efficiency of oxygen in the body.

Excellent youtube video explaining  Circulatory System (credits: Paul Andersen, Bozeman biology )

Q38: Who has longer small intestine tiger or cow?

Answer: Cow because it has to digest cellulose requiring an elaborate digestion. Most of the plant eaters (ruminants)  have to undergo an additional process of digestion i.e. break the cellulose wall and digest it.

Q39: Leaves of a healthy potted plant are coated with Vaseline to block the stomata. Will this plant remain healthy for long? State three reasons to support your answer.

Answer: No the plant will not remain healthy because no exchange of gases is taking place. It will lead to:
  1. low respiration
  2. no photosynthesis occurs
  3. no transpiration.
Hence plant will not remain healthy and may die eventually.

Q40: Outline inhalation-exhalation cycle.

  1. Inhalation: Lowering of diaphragm → rising of rib cage → Gas (O2) passes to Alveoli 
  2. Exhalation: Air is forced out → Rising of diaphragm → lowering of rib cage 

Q41 (CBSE):  Haemoglobin is a type of
(a) Carbohydrate
(b) Skin Pigment
(c) Vitamin
(d) Respiratory Pigment

Answer:  (d) Respiratory Pigment


Answer: The main components of the transport system in human beings are:
  • heart, 
  • blood, and
  • blood vessels.
Heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from various parts of the body and transports this impure blood to the lungs for oxygenation.
Blood is a fluid connective tissue and it helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.

It is a double circulatory system in human body.

Q43: Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Answer: Warm-blooded animals like birds and mammals maintain a constant body temperature under different temperature conditions. They cool themselves in a hotter environment and warm their bodies in a cooler environment. Therefore, these animals need more energy to maintain their body temperature. This requires more cellular respiration which means more oxygen (O2). Therefore it is more efficient if mammals and birds keep separate oxygenated and deoxygenated blood.

Q44(IMP): Why is there extra air in our lungs after exhaling?

Answer: This extra air is called residual volume of air. During the breathing cycle, when the air is taken in and let out, the lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released. Also, we need to do extra work to empty and refill the lungs if there is no residual volume of air inside the lungs.

Q46: Which cell are the site of exchange of gases?

Answer: Alveoli

Q47: How are the lungs designed in human beings to maximise the area for exchange of gases?

  1. Inside the lungs, the blood capillaries surround the alveoli. The exchange of gases takes place between the blood of the capillaries and the gases present in the alveoli. Thus alveoli are the site for exchange of gases. 
  2. During the process of inhalation, the lungs get filled up with air as ribs are lifted up and the diaphragm is flattened.
  3. Air is sucked into the lungs and fills the expanded alveoli. Each lung contains 300-400 million alveoli. These numerous alveoli increase the surface area for gaseous exchange making the process of respiration more efficient.
  4. The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the oxygen in the alveolar air is taken up by blood in the alveolar blood vessels to be transported to all the cells in the body.

Q48: Why blood is necessary for oxygen delivery to all parts of the body in larger animals?

  1. Since the body size of animals is large, the diffusion pressure alone cannot take care of oxygen delivery to all parts of the body. 
  2. Instead, respiratory pigments take up oxygen from the air in the lungs and carry it to tissues which are deficient in oxygen before releasing it. In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen. 
  3. This pigment is present in the red blood corpuscles. Carbon dioxide is more soluble in water than oxygen is and hence is mostly transported in the dissolved form in our blood.

Q49: Define homoeostasis.

Answer: The series of physical and chemical processes that work to maintain an internal equilibrium is called homoeostasis.

Q50: Name the organ systems that help us maintain homoeostasis.

Answer: Circulatory System and Excretory System.

Q51: Wastes concentrated in the tubules of Bowman’s capsule are called ____.
(a) salts.
(b) juices
(c) urine
(d) amino acids

Answer: (c) urine.

Q52: What in kidneys is analogous to alveoli in lungs?

Answer: Nephrons.

Q53(CBSE 2011): State the role and function of lymph in the human transport system.

Answer: Lymph (like blood) is a circulatory fluid. It flows through the lymph vessels.
  1. Lymph (also called tissue fluid) is colourless.
  2. It consists of lymphocytes which kill germs and protect the human body from infections.
  3. Lymph carries digested and absorbed fat from the intestine.
  4. It drains excess fluid from extracellular space back into the blood.
  5. Its flow is unidirectional i.e. from tissues → lymph capillaries → veins → heart.

Q54: What is the basic reason for urine production?

Answer: Blood carries nitrogenous waste in the form of urea or uric acid which needs to be removed. It is done by kidneys by filtering the blood and removing uric acid in the form of urine.

Q55(CBSE 2011): State the role of kidneys in a human transport system.

  1. Remove or excrete nitrogenous wastes
  2. Regulate water content of the body (osmoregulation).
  3. Maintain mineral balance in the blood.

Q56: Who discovered systemic blood circulation system in a human body?

Answer: William Harvey in 1628
Before that people believe, it is the same tubes carry the blood and blood is formed in the liver.

Q57: What is pulmonary circulation and systemic circulation?

Answer: Humans have a double circulatory system. The right side of the four-chambered heart pumps blood to the lungs only and is called the pulmonary circulation.

The left side of the heart pumps blood to the rest of the body is called the systemic circulation.

Q60: Which fluid is also known as tissue fluid?

Answer: Lymph

Q61: What is sphygmomanometer?

Answer: In layman terms, it is called blood pressure apparatus which is used to measure the blood pressure of humans.

Q62: What is the function of ureter?

Answer: Transports urine from kidneys to bladder.

Q63(PreMed):  Assertion and Reason Type
Assertion: Bile is essential for fat digestion
Reason: Fats cannot be digested without emulsification
Use the following Key to choose the appropriate answer.
(a) Both Assertion & Reason are True & Reason is a correct explanation of the Assertion.
(b) If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
(c) If Assertion is True but the Reason is False.
(d) If both Assertion and Reason are False

Answer: (a) Both Assertion & Reason are True & Reason is a correct explanation of the Assertion.

Q64: Chyme is ____.
(a) The digestive enzyme secreted by the stomach.
(b) The hormone secreted by islets of Pancreas
(c) food which enters into the intestine from the stomach.
(d) Part of bile juice which stores in the gallbladder.

Answer: (c) food which enters into the intestine from the stomach.

Q65: What is the nature of Chyme? Acidic or Basic or Neutral?

Answer: Acidic.

Q66: During daytime transpiration and photosynthesis are interlinked. What do you mean by this statement?

Answer: During daytime, stomata are open to diffuse in Carbon Oxide gas for photosynthesis. In parallel, it also facilitates transpiration. Therefore, during daytime the process of transpiration and photosynthesis are interlinked.

Q67: 'Sweating in animals' is equivalent to what in plants?

Answer: Transpiration.

Q68: What factor contribute to rate of transpiration?

  1. Number of leaves
  2. Number of stomata
  3. Temperature of Surroundings
  4. Wind
  5. Water supply
  6. Amount of Light
Q69: How does transpiration help plants?

  1. During transpiration, the evaporating water carries away heat energy. Thus it cools the temperature of plants.
  2. Due to water loss, the osmotic pressure inside leaves decreases. Due to which water and other mineral are able to reach leaves from roots and stem. 
Following you-tube video gives a detailed explanation of Urinary System (Credits: Bozeman Science)

Q70: Name the mineral required for healthy growth of teeth.

Answer: Calcium

Q71: Name the chemical used to detect the presence of starch.

Answer: Iodine

Q72: What is the function of mucus secreted in the stomach during digestion?

Answer: Mucus does not participate directly in the digestion process. However, it protects the inner lining of the stomach due to HCl secretion.

Q73: What is the optimum temperature for photosynthesis?

Answer: 25° C is considered as optimum temperature for photosynthesis.

Q74: Differentiate between Blood and Lymph


Blood                                                      Lymph                                      
1. Reddish in Colour1. Pale Yellow in colour
2. RBCs present2. No RBCs
3. Flow is rapid3.Flow is slow
4. Bidirectional Flow4. Unidirectional
5. Leucocyte count is relatively less.5. High leucocyte count.
6. Platelets present6. Platelets absent

Q75: How does diaphragm help in inhalation?
Answer: It flattens during inhalation, thus increasing the volume of the thoracic cavity.

Q76(HOTS): Why does breathing rate increase at high altitudes or at high mountains?

Answer: At high altitude, the pressure of O₂ falls inside lungs because of low oxygen supply to tissues. So, O₂ is absorbed very quickly from alveoli, thus, increasing breathing rate. Heartbeat also increases to supply the required amount of O₂ to tissues.

Q77: Define heart rate.

Answer: Pulse per minute is called as heart rate. The human heart beats 72 times per minute, this is designated as heart rate. It increases during exercise, fever, anger and fear

Q78: What is a pulse?

Answer: Pulse is the alternate expansion and elastic recoil of an artery with each systole. It is the strongest in the arteries closest to the heart. Therefore, it is also called as an arterial pulse. Normal pulse rate ranges from 70–90 per minute.


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