MCQs, NCERT Chapter Solutions and other Q & A
Q1. The kidneys in human beings are a part of the system for
Answer: (c) excretion.
Q2. The xylem in plants are 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.
(d) all of the above.
Answer: (d) All of the above
Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
Answer: (b) mitochondria
Q5. Movement of food through oesophagus is due to
(a) Lubrication by saliva
(c) Gravitational Pull
(d) All of the above
Answer: (b) Peristalsis
Q6. Where is bile produced?
(a) Gall bladder
Answer: (c) Liver
Q7: In normal expiration, the diaphragm is
(d) None of these
Answer: (a) Arched
Q8: The correct pathway of blood in circulatory system is
(a) atria → ventricles → arteries → veins
(b) ventricles → atria → veins → arteries
(c) ventricles → veins → arteries → atria
(d) veins → ventricles → atria → arteries
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
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:
- Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into sugars (maltose).
- It cleans the mouth cavity and tends to destroy germs that cause teeth decay. It contains lysozymes which help in destroying the bacteria.
- It moistens and lubricates food which again helps in swallowing.
- It acts as solvent, dissolving some food particles to stimulate taste buds of the tongue.
Answer: All cells of 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:
- It is an organized system of molecules that captures energy and nutrients to grow by molecular movements,
- It has the ability to reproduce at some point in its life cycle, and
- It has the potential to evolve in response to changes in the environment.
Answer: It is due to 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:
- Increased surface area
- Highly vascular
Answer: Bile juice is important for the following reasons:
- It contains bile salts and bile pigments that emulsify fats.
- Contains NaHCO3 that neutralizes the acidic medium of the food in small intestine.
Q20: Which organs secrete the following enzymes:
Answer: (i) Trypsin - Pancreas (ii) Pepsin - Gastric lining of Stomach
Q21: Name the factors that affect photosynthesis.
- Light Intensity, its quality and duration.
- Water Availability
- CO3 availability
- Other Factors like age and histology of leaf, amount of chlorophyll present
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:
- light reaction
- 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 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 summarizes 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?
|1||Green plants are self-dependent, because they|
synthesize 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.|
|2||Green Plants (producers) are autotrophs.||Non-Green Plants, Animals, Parasites are hetrotrophs (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.
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 oxidized to provide energy in various organisms?
Answer: Breaking down of glucouse involves 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:
- Aerobic Respiration: In this case, pyruvate is broken down into water and carbon dioxide along with release of energy. It commonly occurs in mitochondria of cells.
- Anaerobic Respiration in Yeast: In yeast cells during fermentation pyruvate is converted into ethanol and carbon dioxide in the absence of oxygen.
- 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 osmo-regulation?
Q32: Which organelle of the cell in animals helps in osmo-regulation?
Answer: Contractile Vacuole.
Q33: If kidney fails to reabsorb water, the tissues would
(a) remain unaffected
(b) shrink to shrivel
(c) absorb water from blood
(d) take more oxygen from blood
Answer: (c) absorb water from blood. This condition is called Oedma or Dropsy
Q34: How does transpiration pull help in 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 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 consist of xylem and phloem. Xylem which have 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.
Answer: In human beings and other vertegrates, 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 body.
- It helps in keeping oxygenated and De-oxygenated blood completely separated.
- It increases the efficiency of oxygen in the body.
Excellent youtube video explaining Circulatory System (credits: Paul Andersen, bozemanbiology )
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 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 are taking place. It will lead to:
- low respiration
- no photosynthesis occur
- no transpiration.
Q40: Outline inhalation-exhalation cycle.
- Inhalation: Lowering of diaphragm → rising of rib cage → Gas (O2) passes to Alveoli
- Exhalation: Air is forced out → Rising of diaphragm → lowering of ribcage
(b) Skin Pigment
(d) Respiratory Pigment
Answer: (d) Respiratory Pigment
Q42: What are the components of the transport system in human beings? What are the functions of these components?
Answer: The main components of the transport system in human beings are:
- blood, and
- blood vessels.
❷Blood is a fluid connective tissue and it helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.
❸The blood vessels (arteries, veins, and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.
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 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?
Q47: How are the lungs designed in human beings to maximize the area for exchange of gases?
- 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.
- During the process of inhalation, the lungs get filled up with air as ribs are lifted up and diaphragm is flattened.
- 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.
- 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.
- Since the body size of animals is large, the diffusion pressure alone cannot take care of oxygen delivery to all parts of the body.
- 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.
- 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 homeostasis.
Answer: The series of physical and chemical processes that work to maintain an internal equilibrium is called homeostasis.
Q50: Name the organ systems that help us maintain homeostasis.
Answer: Circulatory System and Excretory System.
Q51: Wastes concentrated in the tubules of Bowman’s capsule are called ____.
(d) amino acids
Answer: (c) urine.
Q52: What in kidneys is analogous to alveloli in lungs?
Q53(CBSE 2011): State the role and function of lymph in human transport system.
Answer: Lymph (like blood) is a circulatory fluid. It flows in the lymph vessels.
- Lymph (also called tissue fluid) is colourless.
- It consists of lymphocytes which kills germs and protect the human body from infections.
- Lymph carries digested and absorbed fat from intestine.
- It drains excess fluid from extra cellular space back into the blood.
- Its flow is unidirectional i.e. from tissues → lymph capillaries → veins → heart.
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 human transport system.
- Remove or excrete nitrogenous wastes
- Regulate water content of the body (osmo-regulation).
- Maintain mineral balance in blood.
Q56: Who discovered systemic blood circulation system in human body?
Answer: William Harvey in 1628
Before that people believe, it is the same tubes carry the blood and blood is formed in 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 know as tissue fluid?
Q61: What is sphygmomanometer?
Answer: In layman terms it is called blood pressure apparatus which is used to measure 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) Digestive enzyme secreted by stomach.
(b) Hormone secreted by islets of Pancreas
(c) food which enters into intestine from stomach.
(d) Part of bile juice which stores in gall bladder.
Answer: (c) food which enters into intestine from stomach.
Q65: What is the nature of Chyme? Acidic or Basic or Neutral?
Q66: During daytime transpiration and photosynthesis are interlinked. What do you mean by this statement?
Answer: During daytime, stomata is 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?
Q68: What factor contribute to rate of transpiration?
- Number of leaves
- Number of stomata
- Temperature of Surroundings
- Water supply
- Amount of Light
- During transpiration the evaporating water carries away heat energy. Thus it cools the temperature of plants.
- Due to water loss, the osmotic pressure inside leaves decreases. Due to which water and other mineral is able to reach leaves from roots and stem.
Q70: Name the mineral required for healthy growth of teeth.
Q71: Name the chemical used to detect presence of starch.
Q72: What is the function of mucus secreted in stomach during digestion?
Answer: Mucus does not participate directly in digestion. 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
|1. Reddish in Colour||1. Pale Yellow in colour|
|2. RBCs present||2. No RBCs|
|3. Flow is rapid||3.Flow is slow|
|4. Bidirectional Flow||4. Unidirectional|
|5. Leucocyte count is relatively less.||5. High leucocyte count.|
|6. Platelests present||6. Platelets absent|
Q75: How does diaphragm help in inhalation?
Answer: It flattens during inhalation, thus increasing the volume of the thoracic cavity.