HBSE Class 11th Biology Solved Question Paper 2021

HBSE Class 11th Biology Solved Question Paper 2021

HBSE Class 11 Biology Previous Year Question Paper with Answer. HBSE Board Solved Question Paper Class 11 Biology 2021. HBSE 11th Question Paper Download 2021. HBSE Class 11 Biology Paper Solution 2021. Haryana Board Class 11th Biology Question Paper 2021 Pdf Download with Answer. 

Q1. In which class r-Phycoerythrin is the major pigment ? 

(A) Chlorophyceae 

(B) Phaeophyceae

(C) Rhodophyceae 

(D) None of these 

Ans. (C) Rhodophyceae 

Q2. In which phylum closed circulatory system is present ?  

(A) Annelida  

(B) Arthropoda 

(C) Mollusca  

(D) Hemichordata 

Ans. (A) Annelida  

Q3. Glomerulus along with Bowman’s capsule is called : 

(A) Proximal convoluted tubule  

(B) Distal convoluted tubule 

(C) Henle’s loop  

(D) None of these 

Ans. (D) None of these 

Q4. Which of the following acts as auditory receptor ? 

(A) Crista  

(B) Macula 

(C) Organ of corti 

(D) All of these 

Ans. (C) Organ of corti 

Q5. Which of the following have oxygenated blood ? 

(A) Vena cava  

(B) Pulmonary vein 

(C) Right auricle  

(D) Right ventricle 

Ans. (B) Pulmonary vein

Q6. Glycogen is a polymer of :  

(A) Glucose  

(B) Fructose 

(C) Galactose 

(D) Amino acid 

Ans. (A) Glucose  

Q7. In which of the following Synaptonemal complex is formed ? 

(A) Leptotene  

(B) Zygotene 

(C) Pachytene 

(D) Diakinesis  

Ans. (A) Leptotene  

Q8. Which cell organelle is surrounded by single membrane ? 

(A) Lysosome 

(B) Ribosome 

(C) Mitochondria 

(D) Nucleus 

Ans. (A) Lysosome 

Q9. Which of the following is made-up of single layer of cells ? 

(A) Squamous epithelium 

(B) Cuboidal epithelium 

(C) Columnar epithelium  

(D) All of these 

Ans. (D) All of these 

Q10. Phloem fibres are made-up of :  

(A) Parenchymatous cells  

(B) Collenchymatous cells  

(C) Sclerenchymatous cells  

(D) None of these 

Ans. (C) Sclerenchymatous cells  

Q11. Which is having free central placentation ? 

(A) Dianthus  

(B) Mustard 

(C) Sunflower  

(D) Marigold 

Ans. (A) Dianthus  

Q12. The ovary of which flowers is superior ? 

(A) China rose 

(B) Mustard 

(C) Both (A) & (B) 

(D) Cucumber 

Ans. (C) Both (A) & (B)

Q13. Which element play important role in opening and closing of stomata ? 

(A) Nitrogen  

(B) Phosphorus 

(C) Potassium  

(D) Calcium 

Ans. (C) Potassium

Q14. What is zygomorphic flower ?  

Ans. When a flower can be divided into two similar halves  only  in  one  particular  plane.

Q15. What is perigynous flower ? 

Ans. In these flowers, the gynoecium is situated in the centre & other parts of flower are located on the rime  of thalamus  almost  at  the  same  level. 

Q16. What is Venation ? 

Ans. The arrangement of veins and veinlets in the lamina  of leaf. 

Q17. What are pneumatophores ? Give their function.  

Ans. In some plants i.e. Rhizophora growing in swampy areas, many roots come out of the ground & grow vertically upwards, help to get oxygen  for  respiration. 

Q18. What are bulliform cells ? 

Ans. In grasses, certain adaxial epidermal cell along the veins modify themselves into large, empty, colourless  cells. 

Q19. What are heterocysts ? 

Ans. These are specialized cells of some cyanobacteria which  can  fix  atmospheric  nitrogen. 

Q20. Write the name of any two unicellular algae which are used as food supplements even by space travellers.  

Ans. Spirullina & Chlorella

Q21. Write down the name of an oviparous mammal. 

Ans. Ornithorhynchus  (Platypus) 

Q22. From which Latin word ‘systematic’ is derived ? 

Ans. System 

Q23. What are telocentric chromosomes ? 

Ans. Chromose with terminal centromere 

Q24. Which is the most abundant protein in the whole of the biosphere ? 

Ans. Ribulose Biphosphate Carboxylase − Oxygenase (Rubisco) 

Q25. What are the building blocks of nucleic acid ? 

Ans. Nucleotide 

Q26. What is apoenzyme ? 

Ans. Protein portion of the enzyme 

Q27. What does happen in Interphase ? 

Ans. Cell prepare for cell division by undergoing cell growth & DNA replication. 

Q28. In which stage of cell cycle centromere splits & chromatid separates ? 

Ans. Anaphase 

Q29. What is coelom ? 

Ans. The body cavity which is lined by mesoderm.  

Q30. What is photo-phosphorylation ?  

Ans. Photophosphorylation is the synthesis of ATP from ADP and inorganic phosphate in the presence  of light. 

Q31. What is plasmolysis ? 

Ans. When water moves out of cell and the cell membrane of a plant cell shrinks away from its cell wall. 

Q32. Define Growth. 

Ans. An irreversible permanent increase in size of an organ or its parts or even of an individual cell. 

Q33. What is Glisson’s capsule ? 

Ans. Each lobule of liver is covered by thin connective tissue sheath called Glisson’s capsule. 

Q34. Define functional residual capacity of Lungs.  

Ans. Volume of air that will remain in the lungs after a  normal expiration. 

Q35. What is Imbibition ? Give an example. 

Ans. Inhibition is a special type of diffusion  when water is absorbed by solids-colloids-causing them  to  enormously  increase  in  volume.

Ex. Absorption of water by seeds & dry wood. 

Q36. What are the benefits of Diatoms ? 

Ans. Diatoms left behind large amount of cell wall deposits in their habitat which form diatomaceous earth. Diatomaceous earth being gritty, it is used in polishing, filtration of oils & syrups. These are chief producers of oceans. 

Q37. Write down the key features of metaphase of mitosis.  

Ans. Spindle fibres attach to kinetochores of chromosomes. Chromosomes are moved to spindle equator & get aligned along metaphase plate through spindle fibres. 

Q38. What are the functions of melatonin hormone ? 

Ans. It helps in maintaining the normal rhythms of sleep wake cycle, body temperature. Melatonin also influences metabolism pigmentation & menstrual cycle & our defense capability. 

Q39. How is a pinnately compound leaf different from a palmately compound leaf ? 

Ans. In pinnately compound leaf a number of leaflets are present on a common axis, the rachis which represents the mid rib of the leaf but in palmately compound leaves the leaflets are attached at a common point i.e. at the tip of petiole. 

Q40. Write down the physiological responses of Gibberellins in plants.  

Ans. Gibberellins have ability to cause an increase in length of axis. Delay senescence GA3 is used to speed up the malting processing in brewing industry. Gibberellins also promote bolting. Leads to early seed production. 

Q41. Why the Golgi apparatus remains in close association with the Endoplasmic reticulum ? Explain. 

Ans. Golgi apparatus performs the function of packaging material, to be delivered either to the intra-cellular targets or secreted outside the cell. Materials to be packaged in the form of vesicles from the ER fuse with the cis face of the golgi apparatus & move towards the maturing face. Proteins synthesized by ribosomes on the endoplasmic reticulum are modified in the cisternae of the Golgi apparatus before they are released from its transface. 

Q42. Describe modifications of stem with suitable examples.  

Ans. (i) Underground tens are modified to store food in them. Also act as organs of perennation to tide over unfavourable for growth. Ex. Potato, Ginger, Turmeric 

(ii) Stem tendrils : Developed from axillary buds & help plants to climb.  Ex. Cucumber, Pumpkin, etc. 

(iii) Thorns : Axiallary buds of stem modified into woody, straight & point thorns. Ex. Citrus 

Q43. Describe light reaction of photosynthesis. 

Ans. Light reaction of photosynthesis include light absorption, water splitting, oxygen release & the formation of high energy chemical intermediates, ATP & NADPH. The pigments are organized into two photochemical light harvesting complexes within the photosystem I & photosystem II. The LHC are made up of hundreds of pigment molecule bound to proteins. Pigments help to make photosynthesis more efficient by absorbing  different wave lengths of light. Chlorophyll a molecule form reaction centre i.e. different in both the photosynthesis. 

Q44. Write down the important characters of class Chondrichthyes. 

Ans. important characters of class Chondrichthyes : 

(i) There are marine, with streamlined body and cartilagenous endoskeleton.  

(ii) Mouth is located ventrally.  

(iii) Notochord present throughout life. 

(iv) Gill silts are separate without operculum.  

(v) Skin covered by minute placoid scales.  

(vi) Two chambered heart. 

Q45. Describe the process of digestion of food in stomach. 

Ans. Food mixes thoroughly with acidic gastric juice of the stomach by churning movements of its muscular wall called chyme. Pepsinogen on exposure to HCl get converted into active enzyme pepsin which converts protein into proteoses & peptones. HCl provide acidic medium. Rennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion of milk proteins. Small amount of lipases also secreted by gastric glands. 

Q46. Explain the different segments of standard ECG with the help of diagrammatic presentation of a standard ECG. 


P wave– It represents the electrical excitation of the atria or the depolarisation of the atria. It represents the contraction of both the atria. 

QRS complex– It represents the depolarisation of the ventricles which initiates the ventricular contraction. The contractions start shortly after Q and marks the beginning of the systole. 

T- Wave– It represents the return of ventricles from excites to normal state (repolarisation). The end of the T- wave marks the end of systole. 


Describe the structure of Forebrain. 


The brain is mainly divided into three types, as forebrain, midbrain and hindbrain. In these, the forebrain forms the major part of the brain. It is also known as prosencephalon. This part of the brain controls temperature of the body, eating, sleeping, some of the reproductive functions, and conveying of emotions etc.

The forebrain is again divided into cerebrum, Thalamus and hypothalamus.

(i) Cerebrum– It forms the major part of the brain. And its function is necessary for the survival part of the organism. Cerebrum is separated into two hemispheres and these two hemispheres are joined by means of the nerve fibers called corpus callosum. It is covered by a layer of grey matter which is cerebral cortex.

(ii) Thalamus– This part of the fore brain controls the motor and sensory signaling. It is covered by the cerebrum and it lies between the cerebrum and hypothalamus.

(iii) Hypothalamus– This part of the brain lies at the base of all the other forebrain parts. This controls and regulates the temperature of the body, maintains the hungry to eat and thrust to drink by regulating the urge to drink water and eat food. It combines with the parts of cerebrum to control emotional and sexual behavior.

Note- Forebrain maintains the memory, intelligence, will power, sensory and motor activities, consciousness etc. mainly the cerebrum which is also called as telencephalon deals with the language processing, thinking, planning etc.

Q47. Describe Hatch and Slack Pathway.

Ans. Hatch and Slack pathway is a cyclic process. The primary CO2 acceptor is a three-carbon molecule phosphoenolpyruvate (PEP) and it is present in mesophyll cells. The enzyme that catalyses this CO2 fixation is PEP carboxylase or PEPcase. The mesophyll cells pf C4 plants lack the enzyme RuBisCO. The 4-carbon oxaloacetic acid (OAA) is formed in the mesophyll cells. It is then converted to other four-carbon compounds like malic acid or aspartic acid in the mesophyll cells itself, these are then transported to the bundle sheath cells. In the bundle sheath cells, these C4 acids are broken down to release CO2 and three-carbon molecule. The CO2 released in the bundle sheath cells enters the C3 or the Calvin pathway. The bundle sheath cells are rich in an enzyme RuBisCO but lack PEPcase. The three-carbon molecule is transported back to the mesophyll cells where it is converted to PEP again, thus completing the cycle.


Describe TCA (Tri Carboxylic Acid) cycle.  


TCA cycle or Tricarboxylic Cycle is also known as Kreb’s Cycle or Citric Acid Cycle. It is the second stage of cellular respiration that occurs in the matrix of mitochondria. All the enzymes involved in the citric acid cycle are soluble.

It is an aerobic pathway because NADH and FADH2 produced transfer their electrons to the next pathway which will use oxygen. If the transfer of electrons does not occur, no oxidation takes place. Very little ATP is produced during the process directly.

The TCA cycle is a closed loop. The last step of the pathway regenerates the first molecule of the pathway.