RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Rajasthan Board RBSE Class 11 Biology Chapter 27 Meaning of Life

RBSE Class 11 Biology Chapter 27 Multiple Choice Objective Questions

Question 1.
Who called protoplasm as “physical basis of life”.
1. Purkinje
2. Huxley
3. Weismann
4. Darwin

Question 2.
Which sugar found in the milk ?
1. Sucrose
2. Maltose
3. Lactose
4. Glucose

Question 3.
Which one of the following is called as animal starch
1. Glycogen
2. Glycerine
3. Chitin
4. Glucose

Question 4.
Steroids are
1. Simple lipids
2. Conjugated lipids
3. Derived lipids
4. None of the above

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 5.
One of the following is an example of globular protein
1. Histone
2. Keratin
3. Actin
4. Fibrin

Question 6.
Monomer of protein is
1. Glucose
2. Fatty acid
3. Glycerine
4. Amino acid

Question 7.
Which is not a base of DNA
1. Adenine
2. Guanine
3. Uracil
4. Thyamine

Question 8.
Main role of RNA is
1. Transmission of hereditary characters
2. Protein synthesis
3. Regulation of biological activities
4. Temperature control

Question 9.
Flow of energy is always
1. Unidirectional
2. Cyclic
3. Imbalanced
4. None

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 10.
Adaptation is in camel to resist desert environment is/are –
1. Broad pads below the feet
2. Hump with fat tissues
3. Formation of concentrated urine
4. All the above

Answers :
(1). 2
(2). 3
(3). 1
(4). 3
(5). 1
(6). 4
(7). 3
(8). 2
(9). 1
(10). 4

RBSE Class 11 Biology Chapter 27 Very Short Answer Questions

Question 1.
Write the names of major elements found in living beings ?
Answer :
Carbon, Oxygen, Hydrogen & Nitrogen.

Question 2.
Write the names and sources of two disaccharide sugars found in the nature ?
Answer :
Lactose – in milk, Sucrose – in sugar cane.

Question 3.
The exoskeleton in insects in made up of which material?
Answer :
Chitin

Question 4.
Write two examples of conjugated lipids.
Answer :
Phospholipids & glycolipid

Question 5.
Name the protein found in the blood clot.
Answer :
Fibrin

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 6.
Name the small polypeptides formed as a result of incomplete hydrolysis of proteins.
Answer :
Peptones & Proteoses

Question 7.
Write the names of nitrogen bases found in the nucleic acids.
Answer :
Adenine, Guanine, Cytosine, Thymine & Uralic

Question 8.
Write full form of DNA.
Answer :
Deoxyribo Nucleic Acid

Question 9.
Concern to energy flow, what the plants are called.
Answer :
Producers

Question 10.
Give an example of homeostasis.
Answer :
Constant body temperature of human beings

Question 11.
Which type of adaption is found in camel.
Answer :
Desert adaptation

Question 12.
Which part of the brain controls body temperature.
Answer :
Hypothalamus

Question 13.
Which is the most important substance for the growth and formation of new cells.
Answer :
Proteins

Question 14.
Write the full form of ATP.
Answer :
Adenosine-tri-phosphate

Question 15.
Give the examples of saturated & unsaturated fats.
Answer :
Ghee and vegetable oils respectively.

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

RBSE Class 11 Biology Chapter 27 Short Answer Questions

Question 1.
Which fuel matter is mainly used by the cells to get energy? Give a brief account of various categories.
Answer :
Most of the carbohydrates are the constituent of food and are the main source of energy. On the basis of chemical composition, they are of three types-
(A) Monosaccharides
They are simplest carbohydrates which are soluble in water and sweet in taste. They consists of 3 to 7 carbon atoms.

(B) Disaccharides
They are soluble in water and sweet in taste. They consist of two monosaccharides linked by a glycosidic bond. It forms one molecule of water.
RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life img-1
(C) Polysaccharides
They are insoluble in water and tasteless. They are formed by polymerization of monosaccharide units and their general formula is (C6H10O5)n. Starch in plants and Glycogen in animals are two common polysaccharides & they are formed by the polymerization of glucose. Insulin and some others are formed by the polymerization of fructose.

Question 2.
Which types of material the lipids are ? Give three examples.
Answer :
They are also the organic compounds of carbon (C), Hydrogen (H) and Oxygen (O) but there is no specific ratio between hydrogen and oxygen.

Question 3.
Differentiate globular and fibrous proteins.
Answer :
(a) Globular proteins : They are soluble in water.
The polypeptides are coiled and folded. Example : Enzymes, most of the hormones (Insulin, Thyrox-ine), Globins, Histones, Fibrinogen, Protamines, Glutelins etc.

(b) Fibrous proteins : The are insoluble in water.
Their molecules are long, thread-like and contractile. They are structural proteins. Examples : Collagen & Elastin (Found in tendons, cartilages, bones), Keratin (found in skin, nails, horn, hair, feathers), actin & myosin (found in muscles) etc.

Question 4.
What are nucleotides ? Give their chemical structure.
Answer :
They are the units of nucleic acids. Each nucleotide consists of one molecule of phosphoric acid, one molecule of sugar & one molecule of nitrogen base.

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 5.
Draw a labeled diagram of DNA molecule.
Answer :
RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life img-2

Question 6.
Differentiate DNA & RNA.
Answer :

DNA RNA
It consists of deoxyribose sugar It consists of ribose sugar
Presence of thyamine Presence of uracil

Question 7.
What are polysaccharides ? How they are formed.
Answer :
Polysaccharides are complex carbohydrates. They are formed by the condensation of monosaccharides.

Question 8.
Write the functions of lipids in the body.
Answer :
Lipids are the richest source of energy. They are the stored food material.

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 9.
What is entropy ?
Answer :
Entropy is a measure of the disorder or randomness of a system. An ordered system has low entropy. A disordered system has high entropy.

Question 10.
How the body temperature is regulated in man.
Answer :
The body temperature of human beings is 37°C (98°F) which is constant. When the body temperature increases, the blood vessels of the skin dilates to increase peripheral flow of the blood. As a result, the heat radiates out. Simultaneously, the sweat glands activates to secrete more sweat that evaporates and further reduce the body temperature. Excess sweating causes loss of water and salts from the body which may cause dehydration. Hence, our kidneys absorb more water as a result concentrated urine is formed. On the contrary, when the body temperature decreases the skin blood vessels contracts to reduce peripheral blood flow and the heat loss is prevented. This process of temperature control is regulated by the hypothalamus part of the brain.

Question 11.
What is homeostasis ?
Answer :
It is a characteristic of living system that regulates its internal environment and tends to maintain a stable, relatively constant condition of properties. Homeostasis is found in the living bodies naturally i.e. since birth.

Question 12.
Give the role of water in living beings.
Answer :
Water is one of the important substances on earth and it is the basis of life. The life is considered to be evolved in the water. It is essential for the growth and reproduction in the organisms. The human body consists of about 70% water and it forms 70 to 90% part of the living cells. The water is a universal solvent. All the structural bio molecules interact with the help of water. Water provides liquid medium for all the vital activities. It helps in digestion, respiration and excretion. The life can’t survive without water.

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 13.
What are adaptations.
Answer :
Every organism has natural capacity to adapt according to the surrounding environment. Hence, the organisms modify according to the specific environment and survive. Hence, all the modifications and peculiarities in the structure and physiology of an animal according to the environment is called as adaptation.

Question 14.
Write two desert and two aquatic adaption in animals.
Answer :

  • The body is covered by scales or spines to prevent water evaporation.
  • They excrete uric acid to prevent water loss eg. reptiles.
  • Their body is streamlined or boat shaped to minimize friction during swimming.
  • Fishes have lateral line system which is sensory to water pressure & water currents.

Question 15.
Draw a diagram of energy flow in a biosystem.
Answer :
RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life img-3

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

RBSE Class 11 Biology Chapter 27 Essay Type Questions

Question 1.
Describe various types of carbohydrates with examples.
Answer :
Carbohydrates :
They are commonly called as “‘sugar’’. They are maximum among the organic biomolecules found on the earth. They are the organic compounds of carbon (C), hydrogen (H) and oxygon (O) in 1:2:1 ratio. Their general formula is (CH2O)n. They have two or more hydroxyl groups and one aldehyde (-CHO) or ketone (-CO) group. Most of the carbohydrates are the constituent of food and are the main source of energy. On the basis of chemical composition, they are of three types-

(A) Monosaccharides
They are simplest carbohydrates which are soluble in water and sweet in taste. They consists of 3 to 7 carbon atoms.

Glucose, Fructose and Galactose are the 6 carbon containing monosaccharides. Their chemical formula is C6H12O6 and they are isomers. Glucose and fructose are the maximum occurring sugars in the nature. Glucose is also called as dextrose and it is used mainly in the formation of energy. Five carbon containing ribose is another important monosaccharide which participate in the synthesis of DNA and RNA.

Fructose (Fruit sugar) is tire sweetest natural occurring sugar. Tire artificially synthesized Saccharin is about 200-times more sweeter than fructose.

(B) Disaccharides
They are soluble in water and sweet in taste. They consist of two monosaccharides linked by a glycosidic bond. It forms one molecule of water.
RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life img-4
Sucrose (cane sugar), Maltose (fruit sugar) and Lactose (milk sugar) are the examples of disaccharides. Maltose is found in the sprouted grains, sucrose in the sugar can and lactose is found in the milk.

The carbohydrates formed by the condensation of three to ten monosaccharides are called as oligosaccharides.

(C) Polysaccharides
They are insoluble in water and tasteless. They are formed by polymerization of monosaccharide units and their general formula is (C6H10O5)n. Starch in plants and Glycogen in animals are two common polysaccharides &they are formed by the polymerization of glucose. Insulin and some others are formed by the polymerization of fructose. Glycogen is also called as Animal Starch

The polysaccharides are normally the stored food material in the animals and plants because they hydrolyses easily to form monosaccharides.

Cellulose and Chitin are also polysaccharides. The cellulose is used in the formation of cell wall in the plants and the chitin is used in the formation of exoskeleton of insects and other arthropods. Significance of Carbohydrates

  • They are the primary source of energy.
  • They are used in the formation of cell wall and connective tissues.
  • Starch in plants and glycogen in animals are the stored form of food.
  • Chitin is used in the formation of exoskeleton of insects & other arthropods.
  • Ribose is used in the formation of RNA and DNA.

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 2.
What are lipids chemically ? Describe the types of lipids.
Answer :
Lipids or Fats :
They are also the organic compounds of carbon (C), Hydrogen (H) and Oxygen (O) but there is no specific ratio between hydrogen and oxygen.

The bonds between carbon and hydrogen are covalent and non-polar. The lipids are insoluble in water but they are soluble in organic solvents like ether, chloroform, benzene etc.

In animals lipids are found in the form of fats. The fats are made up of fatty acids and glycerol. One molecule of fat is formed by the union of three molecules of fatty acids and one molecule of glycerol.
The lipids are of three types viz. –

(A) Simple Lipids
They are the simple lipids and are true fats. They are also called as storage lipids. Three molecules of fatty acids react with one molecule of glycerol to form one molecule of simple lipid and three molecules of water.
RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life img-5
Most of the plant fats are unsaturated which have double or triple bonds. Such as vegetable oils like groundnut oil, mustard oil, sesame oil etc.
Most of the animal fats are saturated which consists of single bonds. Such as ghee, butter, grease etc.

(B) Conjugated or Compound or Complex Lipids
They are made up of fatty acids, glycerol and other organic or inorganic group.

Examples – Phosphoplipids (Lecithin, Cephalin), Glycolipids (Cereprosides, Gangliosides, Globosides), Aminolipids (Seresin, Sphingosine), Sulpholipids etc.

Functionally, they are structural lipids which participate in the formation of the biological membranes.

(C) Derived Lipids
They are formed as result of hydrolysis of simple or conjugated lipids. Example – Steroids (sexual hormones, vitamin D), Sterols (cholesterol, carotenoids) etc.)
Constant intake of large quantity of fatty food increases cholesterol in the blood. The cholesterol along with other substances get deposited inside the blood vessels and may lead to heart attack.

Functions of Lipids :

  • They are the richest source of energy. They have about 2.25 times more energy than carbohydrates.
  • Many hormones and vitamins are made up of lipids.
  • They help to regulate body temperature.
  • They are used as reserve food.
  • Saponification of true lipids form soap.
  • They are used as lubricant.

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 3.
Describe the categories and subcategories of the proteins with examples.
Answer :
Proteins are the most abundant molecules in the living cells. Chemically, they are the organic compounds of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). They may contain phosphorus (P), sulphur (S) and magnesium (Mg). Proteins are large and complex molecules. The body consists of about 14 to 16% of proteins.

The proteins are made up of amino acids i.e. amino acid is the structure unit or monomer of the proteins. There are many types of amino acids but only 20 types of amino acids participate in the formation of proteins which are called as fundamental amino acids or manufacturing amino acids.

In protein formation, the amino acid join with the help of peptide bonds. The peptide bond is a functional unit of proteins. Therefore, the proteins are also called as polypeptide chains.

On the basis of chemical composition, the bioproteins are of three bytes viz. –

(A) Simple or Pure Proteins :
They are made up of only amino acids. They are of two types-

(a) Globular proteins : They are soluble in water. The polypeptides are coiled and folded. Example : Enzymes. Most of the Hormones (Insulin, Thyroxine), Globins, Histones, Fibrinogen, Protamines, Glutelins etc.
(b) Fibrous proteins : The are insoluble in water. Their molecules are long, thread-like and contractile. They are structural proteins. Examples : Collagen & Elastin (Found in tendons, cartilages, bones), Keratin (found in skin, nails, horn, hair, feathers), Actin & Myosin (found in muscles) etc.

(B) Conjugated protein :
They are made up of amino acids and other organic or inorganic group. The other group is called as prosthetic group. They are as follows-

(a) Phosphoproteins : It’s prosthetic group is phosphorus. Example : Milkcaosin.
(b) Nucleoproteins : The prosthetic group is nucleic acid. Example : Chromatin (Histone + Nucleic acid)
(c) Glycoproteins or Mucoproteins : The prosthetic group is carbohy drate. Example : Globulin, Mucus etc.
(d) Chromoproteins : They are coloured proteins. Examples : Haemoglobin, Haemocyanin, Cytochrome, Chlorophyll etc.
(e) Lipoproteins : Their prosthetic group is lipid. Examples : Lipovitellin etc.

(C) Derived proteins :
They are formed by the enzymatic or chemical hydrolysis of simple or conjugated proteins.
Examples : Peptones, Proteoses, Fibrin etc.

Functions of Proteins :

  • They are the building blocks of the body.
  • They help in body growth and repairing of body tissues.
  • All enzymes (biocatalyst) are made up of proteins.
  • Most of the hormones are made up of proteins.
  • Hemoglobin, haemocyanin etc. act as respiratory pigment which transport O2.
  • Globulin proteins form antibodies.
  • Actin and myosin are contractile proteins found in the muscles.
  • Fibrinogen participate in blood clotting.
  • Keratin forms nail, claws, horn hair etc.

Table showing 20 types of fundamental amino acids

(A) Essential Amino Acids (B) Non-essential Amino Acids
1. Arginine – Arg
2.  Histidine – His
3.   Isoleucine – lie
4.   Leucine – Leu
5.  Lysine – Lys
6.   Phenylalanine – Phe
7.  Threonine – Thr
8.  Tryptophane – Try
9. Valine-Val
1. Alanine – Ala
2. Aspartic acid – Asp
3.  Asparagine – Asn
4.   Cysteine – Cys
5. Glutamic acid – Glu
6.  Prolin – Pro
7. Glutamine – Gln
8.  Serine – Ser
9. Tyrosine – Tyr

RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life

Question 4.
Give an account of energy flow in the nature.
Answer :
All the living organisms requires energy to perform vital activities. They obtain energy by different ways and use it in various body functions. The animals obtain energy from plants and other organisms in the form of food.

The flow of energy in the nature is unidirectional. The green plants traps solar radiations and convert them into chemical energy by the process of photosynthesis. Hence the plants are called as producers. The herbivorous animals feed on plants to get energy and are called as primary consumers. From the herbivores, in turn are eaten by carnivores and predators which are called as secondary and tertiary consumers respectively. The decomposers (microorganisms) feed on dead energy which finally lost in the environment. Hence, the solar energy passes through the various levels of the biological system and finally lost in the environment. It never returns to the sun. Hence, it is called as unidirectional flow of energy.

The total energy in a biological system, both usable and decayed energy, is called as Enthalpy. The usable energy which is available to perform the work is called as free energy.

According to the first law of thermodynamics (law of conversion), the energy is neither be created nor destroyed in an isolated system. It can be converted from one form to another form.

According to second law of thermodynamics, the state of entropy of the entire universe will always increase overtime. Further, the changes in the entropy in the universe can never be negative.
There is constant flow of energy in biological system.
RBSE Solutions for Class 11 Biology Chapter 27 Meaning of Life img-6

Question 5.
What is adaptation ? Give a detail account of adaptations found in the animals.
Answer :
Adaptation :
Every organism has natural capacity to adapt according to the surrounding environment. Hence, the organisms modify according to the specific environment and survive. Hence, all the modifications and peculiarities in the structure and physiology of an animal according to the environment is called as adaptation.

As a result of adaptation, the animal develops harmony with the environment. For example, in the aquatic animals the body becomes streamlined (boat shaped) to ease swimming. Similarity, the body of flyer animals is light and they have wings.

Desert adaptations :
The mam factors in the desert climates arc deficiency of water, extremes of temperature, dust storms & feeble vegetation. In the desert, the day temperature is very high and the night temperature is very low. Hence, the desert animals experience extremes of temperature twice in a day.

Such animals have efficient capacity to conserve water. Their skin is hygroscopic and covered by thick dermal scales. The desert animals exhibit following main adaptions –

  • The body is covered by scales or spines to prevent water evaporation.
  • They excrete uric acid to prevent water loss eg. reptiles.
  • Camel can survive without drinking water in the desert for a long period. They have lots of different adaptations. For example, they have hump which store large fat and this fat provides metabolic water. Their RBC are oval rather than circular which makes them better at withstanding the osmotic changes when they are dehydrated. They may obtain moisture from plants they consume.
  • The feet of camel are broad, flat and have leathery pads at the bottom to walk on the sand.

Aquatic adaptations :
Most of the animals on the earth are aquatic (both marine & fresh water). They are well adapted to their aquatic life. Some of the adaptations are as follows –

  • Their body is streamlined or boat shaped to minimize friction during swimming.
  • Fishes have lateral line system which is sensory to water pressure & water currents.
  • Some fishes have air bladder which provides buoyancy in addition to assist respiration.
  • They develops certain organs for swimming. For example in whale, the fore limbs modify to from flippers. The fishes have fins for swimming.

RBSE Solutions for Class 11 Biology