students must start practicing the questions from CBSE Sample Papers for Class 11 Biology with Solutions Set 8 are designed as per the revised syllabus.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

Time Allowed : 3 hours
Maximum Marks: 70

General Instructions :

  1. All questions are compulsory.
  2. The question paper has four sections: Section A, Section B, Section C and Section D. There are 27 questions in the question paper.
  3. Sedion-A has 5 questions ofl mark each. Section-B has 7 questions of 2 marks each. Section-C has 12 questions of 3 marks each and Section-D has 3 questions of 5 marks each.
  4. There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
  5. Wherever necessary, neat and properly labelled diagrams should be drawn.

Section – A

Question 1.
Apples are generally wrapped in waxed paper to:
(A) Prevent sunlight for changing its colour.
(B) Prevent aerobic respiration by checking the entry of O2.
(C) Prevent ethylene formation due to injury.
(D) Make the apples look attractive.
Answer:
(B) Prevent aerobic respiration by checking the entry of O2.
Explanation: Prevent aerobic respiration by checking the entry of O2

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

Question 2.
What is a Tonoplast?
(A) Outer membrane of mitochondria.
(B) Inner membrane of the chloroplast.
(C) Membrane boundary of the vacuole of plant cells.
(D) Cell membrane of a plant cell.
Answer:
(C) Membrane boundary of the vacuole of plant cells.

Question 3.
Mark the incorrect statement in context to O2 binding to Hb:
(A) Higher pH.
(B) Lower temperature.
(C) Lower pCO2.
(D) Higher pO2.
Answer:
(A) Higher pH.

Question 4.
Assertion (A): The PNS comprises of all the nerves of the body associated with CNS.
Reason (R): PNS is the site of information processing and control.
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(C) A is true but R is false.
(D) A is false and R is true.
Answer:
(C) A is true but R is false.
Explanation:
The PNS comprises of all the nerves of the body associated with the CNS while the brain and the spinal cord are the site of information processing and control.

Question 5.
Assertion: Sweat is considered as an excretory waste.
Reason: It contains nitrogenous wastes, dissolved salts and excess of water.
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(Q A is true but R is false.
(D) A is false and R is true.
Answer:
(A) Both A and R are true, and R is the correct explanation of A.
Explanation:
Sweat is considered as an excretory waste because it contains nitrogenous wastes, dissolved salts and excess of water.

Section – B

Question 6.
What are the rules of binomial nomenclature?
OR
What makes a species a basic taxonomic category?
Answer:
Rules of nomenclature are as follows:

  1. Biological names are generally in Latin or derived from Latin irrespective of their origin.
  2. The first word in a biological name represents the genus while the second component denotes the specific epithet.
  3. The words when handwritten are separately underlined, or printed in italics.
  4.  The first word denoting the genus starts with a capital letter while the specific epithet starts with a small letter.

OR
Species consists of one or more individuals that resemble one another more closely than individuals of other species. The members of a species interbreed freely and are reproductively isolated from members of other species. These features make the species a basic taxonomic category.

Question 7.
How many types of roots are found in plants?
Answer:
There are generally three types of roots. They are:

  1. Tap root: The root which develops from radical along with its branches is termed as tap root. Secondary root develops from tap root.
  2. Fibrous Root: In monocot plants, the primary root is short-lived and is replaced by roots that arise from the stem. These roots constitute the fibrous roots.
  3. Adventitious root: Roots which arise from other parts of the plant except radical are termed as adventitious roots.

Question 8.
What are the similarities between algae and fungi?
Answer:

  • They occur in aquatic and semi-aquatic habitats.
  • Both have simple body called thallus, which is not differentiated into roots, stem and leaves.
  • Asexual reproduction occurs by microspores.
  • Sex organs are unisexual and non-jacketed.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

Question 9.
Plants require water for their survival. But when watered excessively, plants die. Discuss.
Answer:
Water is necessary for the survival of plants. However, when water is present excessively, it dies because excess water replaces and removes the air trapped between the soil particles. So, plants do not get enough oxygen for respiration. Once root cells die, water and mineral absorption is stopped and this leads to the gradual death of the plant.

Question 10.
Why anaerobic respiration yields much less energy than aerobic respiration?
Answer:
Anaerobic respiration yields much less energy than aerobic respiration. The main reasons are:

  • There is an incomplete breakdown of the respiratory substrate.
  • One of the end products of anaerobic respiration is organic that still contains energy.
  • NADH2 produced during glycolysis is often reutilised.
  • Regeneration of NAD+ from NADH2 does not produce ATE
  • Electron transport chain is absent.
  • Oxygen is not used for accepting electrons and protons.

Question 11.
What are the two factors that contribute towards the dissociation of oxyhaemoglobin in the arterial blood to release
molecular oxygen in an active tissue?
Answer:
The two factors that contributes towards the dissociation of oxyhaemoglobin in the arterial blood to release molecular oxygen in an active tissue are

  • Lower concentration of pO2
  • Higher concentration of pCO2

Question 12.
How locomotion is different from movement?
Answer:
The movement of an individual from one place to another is called locomotion. It includes walking, running, crawling, hopping, flying or swimming. Movement is the motion of body parts with respect to the body axis.

Section – C

Question 13.
Give the difference between the cell walls of Gram-positive and Gram-negative bacteria.
Answer:
Difference between cell walls of Gram-positive and Gram-negative:

Cell walls of Gram-positive bacteria Cell walls of Gram-negative bacteria
(i) Their cell wall is single-layered and 100-200 A thick. Their cell wall consists of two layers and is 70-120 A in thickness.
(ii) They can be stained by gram stain. They cannot be stained by gram stain.
(iii) The lipid content of the wall is quite low. The lipid content of the wall is 20-30%

Question 14.
What is metamerism? Differentiate between metameric and non-metameric segmentation?
Answer:
Segmentation of external and internal body into linear sequence of segments (repetition of at least some organ) is called metamerism.

Metameric Segmentation:
External segmentation corresponds to internal segmentation, e.g., Earthworm. Non-metameric Segmentation: External segmentation do not correspond internal segmentation, e.g., Platyhelminthes.

Question 15.
Describe the primary, secondary and tertiary structure of a protein?
Answer:
(i) Primary Structure: The linear sequence of amino add units in a polypeptide chain is called the primary structure of a protein molecule. Ribonuclease is an enzyme having a protein with primary structure only.

Secondary Structure:
The polypeptide chain that forms a 3-dimensional structure, is called as secondary structure.

It possesses three forms:

  1. a helix: The coils of the helix are held together by hydrogen bonds between amino adds.
  2.  p helix: More than one chain lies side by side joined together by hydrogen bonds between the carboxyl group of amino adds.
  3. Collagen proteins: It is a right-handed superhelix formed by the twisting of three helices of polypeptide chains intertwined with each other.

Tertiary Structure:
The tertiary structure of protein brings distant amino to add side chains nearer to form active sites of enzyme proteins. The tertiary structure is maintained by weak bonds, such as hydrogen, ionic and hydrophilic hydrophobic bonds, formed between one part of a polypeptide and another. The biological activity of a protein molecule depends largely on the spedfic tertiary structure. Tertiary structure is found in globular proteins.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

Question 16.
Describe the six important properties of enzymes.
Answer:
products. The properties of enzymes are:

  1. Enzymes are generally globular proteins. They may have additional inorganic or organic substance for their activity.
  2. Being proteinaceous, the enzymes are giant molecules with a molecular weight of 6s000 to 4,600,000.
  3. Enzymes have colloidal nature. They are hydrophilic and form hydrosol in the free state.
  4. Enzymes are in no way transformed or used up in the chemical reaction but come out unchanged at the end of reaction.
  5. All enzyme-controlled reactions are reversible. Reversibility is dependent upon energy requirements, availability of reactants, concentration of products and pH.
  6. Enzymes are highly specific in their action. For example, the enzyme maltase acts on sugar maltose but not on lactose or sucrose. Different enzymes may act on tire same substrate but gwe rise to different

Question 17.
What are lichens? Give any two uses of lichens.
OR
How do viruses resemble with the living beings?
Answer:
Lichens are the composite or dual organisms representing a symbiotic assodation between a fungus and alga. The fungal partner is called mycobiont whereas algal partner is called phycobiont. Algae prepares food for fungi and fungi provides shelter and absorbs mineral nutrient and water for its partner. Lichens grow on barren rocks, cooled volcanic lava and icy tundra soils. They can tolerate extreme dessication but not the polluted air.

Importance of lichens:

  1. Litmus used as pH indicator was prepared from lichen Roccella tinctoria.
  2. Scented incense or perfumes are obtained, from Ramalina and Evernia.
  3. Lichens acts as pollution indicators.
  4. Certain lichens are the source of food for grazing animals.

OR
Viruses resembles with living beings in the following manner;

  • It is formed of organic macromolecules, which occur only in living beings.
  • Presence of genetic material.
  • Ability to multiply or reproduce.
  • Occurrence of mutations. The most mutable virus is HIV.
  • Occurrence of enzyme transcriptase in most viruses.
  • They breed true to their type. Even variations are inheritable.
  • They take over the biosynthetic machinery of the host cell and produce chemicals required for multiplication.

Question 18.
What is the role of sarcoplasmic reticulum, myosin head and F-actin during contraction of striated muscles of
hormones?
Answer:

  1. 1Sarcoplasmic reticulum: It releases calcium ions into the sarcoplasm that binds to troponin causing a change in its shape and position and thereby removing the masking of active sites for myosin.
  2. Myosin head: The myosin head is an active ATPase enzyme and has binding sites for ATP and active sites for actin. It binds to the exposed active sites on actin to form a cross bridge.
  3. F-actin: The actin sites on the F-actin are specific to the myosin head for cross-bridge formation.

Question 19.
Under what conditions are C4 plants superior to C3?
Answer:
C4 plants are superior to C3 as:

  • They have a special type of leaf anatomy.
  • They can tolerate higher temperatures and highO2 concentration, as the enzyme PEP carboxylase in C4 cycle is insensitive to oxygen and does not show photorespiration.
  • They lack a process called photorespiration and have greater productivity of biomass.
  • hey show a response to high light intensities
  • They are more efficient in picking up CO2 even at low concentration in the atmosphere.

Question 20.
Frog is a poikilotherm, exhibits camouflage and undergoes aestivation and hibernation, how are all these beneficial to it?
OR
What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.
Answer:
Frog, being poikilotherm cannot withstand cold weather and high temperature. Thus, it buries itself deep in mud during winters and summer This phenomenon is known as hibernation (winter sleep) and aestivation (summer- sleep) respectively. During this period, it lives in a dormant stage with very minimal vital body activities.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions
OR

  1. Each stoma is made of two bean-shaped cells called the guard cells.
  2. These are dumbbell shaped in monocots like grasses.
  3. The guard cells possess chloroplast.
  4. Guard cells regulate the opening and closing of stomata.
  5. Some epidermal cells in the vicinity of guard cells become specialized in shape and size and they are termed as the subsidiary cells.
  6. The stomatal aperture (pore), the guard cells, and the surrounding subsidiary cells make the stomatal apparatus.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions 1

Question 21.
Write an account of various types of fruits.
Answer:
Fruit: The ripened and matured ovary after fertilisation is called ‘fruit.

  1. In some plants, the ovary and other floral parts may turn into the fruit without fertilisation. The fruits without fertilisation are called ‘Parthenocarpic fruit’ or ‘Seedless fruit’ for e.g., Banana.
  2. True and False fruits: The fruits which are developed from the fertilised ovary are called true fruits, e.g., Pea, Maize, Wheat, etc.
  3. The fruits developed from other non-essential parts of the flower (such as sepals, petals, thalamus, etc.) are called ‘false fruit’ or ‘Pseudocarpic fruits’. For e.g., apple (thalamus is edible).

Question 22.
Explain the following:

  1. There will be no life without photosynthesis.
  2. There is no oxygen evolution in bacterial photosynthesis.
  3. Chlorophyll is an essential photosynthetic pigment.

Answer:
1. For existence of life, food and O2 are very essential. Photosynthesis is the only process that can trap solar
energy and can synthesize food for own and all other organisms. During photosynthesis, O2 is given out and CO2 is taken. So, it keeps the balance of O2 and CO2 in nature. Thus, photosynthesis is essential for existence of life.

2. In bacterial photosynthesis, the raw material of the supply of proton (H+) is H2S than H2O.
Thus, there is the production of sulphur and not oxygen.

3. Chlorophyll-b and other pigments of a reaction centre or photosystem absorb solar energy and transfer it to chlorophyll-a. Ultimately it is the chlorophyll-a that initiates the photosynthesis process.

Question 23.
(a) What are the uses of ethylene?
(b) Name one synthetic auxin that can be used as a herbicide.
OR
Explain the counteraction of cytokinin on apical dominance.
Answer:
(a) Uses of ethylene are as follows:

  • Ethephon hastens fruit ripening in tomatoes and apples.
  • Increase in the number of fruits.
  • Sprouting of storage organs such as rhizomes, corms, and tubers can be enhanced by exposing them to ethylene.
  • Ethylene accelerates abscission in flowers and fruits and is used for thinning of fruits like cotton, cherry, etc.

(b) 2, 4-dichloro phenoxy acetic acid (2, 4-D) is a dicotyledonous weed killer. 2, 4-D is used to kill broad-leaved weeds. It is used to induce flowering in pineapple and litchi.
OR

  1. Auxins and cytokinins act antagonistically in relation to apical dominance.
  2. The auxins allow dominance of apical bud while cytokinins stimulate the growth of lateral buds.
  3. Application of cytokirrins to lateral buds relieves them from apical inhibition.
  4. In the presence of cytokinins, supply of water and minerals increases to these buds, and therefore, the lateral buds grow even in the presence of apical bud.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

Question 24.
How does exchange of respiratory gases takes place in the alveoli of lungs?
Answer:

  1. During the uptake of air the partial pressure of oxygen and pCO2 are 159 mm Hg and 0.3 mm Hg respectively.
  2. There is already a small amount of alveolar air in the lungs. This air contains less amount of O2 and more CO2 than the inspired air.
  3. As this alveolar air mixes with the inspired air then O2 is counted and pO2 of alveolar air increases to 13.1% and 100 mm Hg whereas CO2 content and pCO2 is 5.3% and 40 mm Hg.
  4. The pulmonary artery brings the deoxygenated blood from the heart to the lungs.
  5. The blood consists of lower pO2 than alveolar pO2.
  6. In the lungs, O2 diffuses into the blood from the alveolar air and pO2 which is 95 mm Hg increases by 19.8%.
  7. This oxygenated blood is taken away by the pulmonary vein.
  8. This blood in alveolar capillaries contains pCO2 which falls to 40 mm Hg.
  9. In the alveoli of the lungs O2 is taken up by vein and CO2 is given out from blood through artery

Section – D

Question 25.
(a) A plant species shows several morphological variations in response to the latitudinal gradient. When grown
under similar conditions of growth, the morphological variations disappear and all the variants have common morphology. What are these variants called? 2+1+2

(b) What is the difference between monotypic and polytypic genus?

(c) What are the drawbacks of the two kingdom classification system?
Answer:
(a) These morphological variants are called biotypes. Biotypes are group of genetically similar plants which show similarity when grown in the same environmental and geographical regions. The same environment provides them the similar abiotic factors like soil, pH, temperature, etc. When such plants are grown in two different geographical regions, they are exposed to different abiotic characters. This in turn, affects their growth and development and brings changes in their external morphological features, but their genetic constitution remains same.

(b) When genus consist of only one existing species it is called as monotypic genus and when it consists of many species it is said to be as polytypic genus.

(c) Carolus Linnaeus anciently divided all living organisms into two kingdoms: Plantae and Animalia.
The drawbacks of this classification are:

  1. First-formed animals were neither plants nor animals.
  2. Fungi differ in structure, physiology and reproductively from plants.
  3. At lower level of organisation there are several instances where the distinction of plant and animal disappears.

Question 26.
Read the following to answer the questions with explanation from (i) to (v) given below: 5×1=5
The entire heart is made of cardiac muscles. The walls of ventricles are much thicker than that of the atria. A specialised cardiac musculature called the nodal tissue is also distributed in the heart. A patch of this tissue is present in the right upper corner of the right atrium caEed the sino-atrial node (SAN). Another mass of this tissue is seen in the lower left corner of the right atrium close to the atrio-ventricular septum called the atrio-ventricular node (AVN). A bundle of nodal fibres, atrioventricular bundle (AV bundle) continues from the AVN which passes through the atrio-ventricular septa to emerge on the top of the interventricular septum and immediately divides into a right and left bundle.

These branches give rise to minute fibres throughout the ventricular musculature of the respective sides and are called purkinje fibres. The nodal musculature has the ability to generate action potentials without any external stimuli, i.e., it is auto excitable. However, the number of action potentials that could be generated in a minute vary at different parts of the nodal system. The SAN can generate the maximum number of action potentials, i.e., 70-75 min’1, and is responsible for initiating and maintaining the rhythmic contractile activity of the heart.

(i) What is SA node?
Answer:
A patch of nodal tissue is present in the right upper corner of the right atrium called the sino-atrial node.

(ii) State the formation of purkinje fibres.
Answer:
A bundle of nodal fibres, atrioventricular bundle continues from the AVN which passes through the atrio-ventricular septa to emerge on the top of the interventricular septum and immediately divides into a right and left bundle. These branches give rise to minute fibers throughout the ventricular musculature of the respective sides and are called purkinje fibers.

(iii) Which part of the heart is auto excitable?
Answer:
Sino-atrial node is autoexcitable.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

(iv) Which part of the heart is called heart of the heart?
Answer:
The sino-atrial node is called heart of the heart.

(v) How many Purkinje fibres are found in a heart
Answer:
There are two purkinjei fibers found in a the heart.

Question 27.
Read the following to answer the questions from (i) to (v) given below:( 5×1=5)
The fusion of two gametes during sexual reproduction, each with a complete haploid set of chromosomes result in the production of offspring. Gametes are formed from specialised diploid cells. This type of division is called meiosis. Meiosis reduces the chromosome number by half which results in the production of haploid daughter cells. This cell division ensures the production of haploid phase in the life cycle of sexually reproducing organisms whereas fertilisation restores the diploid phase. Meiosis occurs during gametogenesis in plants and animals. This leads to the formation of haploid gametes.

The main features of meiosis are:
It involves two sequential cycles of nuclear and cell division called meiosis I and meiosis II but only a single
cycle of DNA replication. Meiosis I starts only after the parental chromosomes have replicated to produce identical sister chromatids at the S phase. Meiosis involves pairing of homologous chromosomes and recombination between them. At the end of meiosis II, four haploid cells are formed.

(i) Meiosis results in:
(A) Production of gametes
(B) Reduction in the number of chromosomes
(C) Introduction of variation
(D) All of the above
Answer:
(D) All of the above
Explanation:
Meiosis occurs during gametogenesis in plants and animals, This results in the production of haploid gametes. Meiosis I results in the number of chromosomes and crossing over during pachytene and Meiosis I results in the introduction of variation.

(ii) At which stage of meiosis does the genetic constitution of gametes is finally decided?
(A) Metaphase I
(C) Metaphase II
(B) Anaphase II
(D) Anaphase I
Answer:
(D) Anaphase I
Explanation:
Segments of non sister chromatids of homologous chromosomes get exchanged during pachytene of Meiosis I. Chromosomes with exchanged segments are reconstituted at the end of meiosis I and separating during anaphase I, This finally decides the genetic constitution of gametes.

(iii) A bivalent of meiosis-I consists of:
(A) Two chromatids and one centromere
(C) Four chromatids and two centromeres
(B) Two chromatids and two centromeres
(D) Four chromatids and four centromeres
Answer:
(C) Four chromatids and two centromeres
Explanation:
During zygotene of prophase I of meiosis the homologous chromosomes undergo pairing (Synapsis). This pair of chromosomes is called bivalent. Each chromosome of bivalent undergo longitudinal splitting giving rise to a tetrad. Thus, there are four chromatids of two centromeres in meiosis-I.

(iv) Identify the wrong statement about meiosis.
(A) Pairing of homologous chromosomes.
(B) Four haploid cells are formed.
(C) At the end of meiosis, the number of chromosomes is reduced to half.
(D) Two cycle of DNA replication occurs.
Answer:
(D) Two cycle of DNA replication occurs.
Explanation:
There is only one cycle of DNA replication and this occurs in ‘S’ or synthetic phase of cell cycle.

CBSE Sample Papers for Class 11 Biology Set 8 with Solutions

(v) Direction: In the following questions the Assertions (A) and Reasons (R) have been put forward. Read both the statements and choose the correct option from the following:
Assertion (A): Meiosis is also known as ‘Reduction Division.
Reason (R): The chromosomes replicate and get equally distributed both quantitatively and qualitatively into
two daughter cells.
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is not the correct explanation of A.
(C) A is true but R is false.
(D) A is false but R is true.
Answer:
(C) A is true but R is false.
Explanation:
Meiosis is called as reduction division because the chromosome number gets reduced to its half. It helps in producing haploid gametes in sexually reproducing organisms.