10th Biology Important Questions with Answers

Master your diagrams and technical vocabulary with our expert-compiled guide to 10th Biology Important Questions. Scoring high in Biology demands a perfect balance of clear conceptual definitions, accurate naming of processes, and clean, labeled structural diagrams. This comprehensive archive narrows down the most high-yield topics across your entire syllabus—from life processes and control pathways to heredity, reproduction, and the environment. Whether you are reviewing core life cycles or practicing structured long answers, these questions provide a strategic roadmap to maximize your study efficiency and secure full marks.

CHAPTER 12-22 • GRADE X

10TH SCIENCE (BIOLOGY)

IMPORTANT QUESTIONS

1. What is a collateral vascular bundle?

It is a type of conjoint vascular bundle.
Xylem lies towards the center and phloem lies towards the periphery.
When cambium is present in collateral bundles, it is called open. e.g. dicot stem
Collateral bundle without cambium is called closed. E.g. monocot stem.

2. Name the three basic tissue systems in flowering plants.

Dermal Tissue System: Protects the plant (e.g., epidermis).
Ground Tissue System: Provides support, storage, and photosynthesis (e.g., parenchyma, collenchyma, and sclerenchyma).
Vascular Tissue System: Conducts water, minerals, and food (e.g., xylem and phloem).

3. What is Respiratory quotient?

Respiratory quotient is the ratio of volume of carbon dioxide liberated and the volume of oxygen consumed during respiration. It is expressed as:

RQ = Volume of CO₂ Liberated / Volume of O₂ Consumed

4. Differentiate the Following:

a) Monocot Root vs Dicot Root

Feature	Monocot Root	Dicot Root
Number of Xylem Bundles	Polyarch	Tetrarch
Cambium	Absent	Present
Secondary Growth	Absent	Present
Pith	Present	Absent
Conjunctive Tissue	Sclerenchyma	Parenchyma
Example	Maize, Grass	Bean, Sunflower

b) Aerobic vs Anaerobic Respiration

Aerobic Respiration	Anaerobic Respiration
Complete oxidation of glucose using oxygen	Breakdown of glucose without using oxygen
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP	C₆H₁₂O₆ → 2CO₂ + 2C₂H₅OH + ATP
End products are Carbon dioxide (CO₂), water (H₂O), and ATP	End products are Ethanol and carbon dioxide (in yeast) or lactic acid (in bacteria)
High energy is produced	Low energy is produced
Complex process (Three stages – 1. Glycolysis, 2. Krebs Cycle, 3. Electron Transport Chain)	Simple process (Glycolysis)

5. How does leech respire?

Leeches respire through their skin by diffusion of gases.

6. How is diastema formed in rabbit?

Diastema is formed due to the absence of canine teeth. It helps in mastication and chewing of food.

7. What does CNS stand for?

CNS stands for Central Nervous System.

8. How does leech suck blood from the host?

Leech sucks blood using its muscular pharynx and secretes hirudin to prevent blood clotting.

9. List out the parasitic adaptations in leech.

The parasitic adaptations in leech are:

Suckers: Anterior and posterior suckers help the leech attach to the host.
Pharynx: Sucks blood from the host.
Three jaws create a painless Y-shaped wound.
Hirudin: Prevents blood clotting, ensuring a continuous blood supply.
No Parapodia or Setae.
Crop Storage: Blood stored in the crop provides nourishment for months, reducing the need for digestive enzymes.

10. How does locomotion take place in leech?

Locomotion in leech occurs through two methods:

Looping or crawling movement: This type of movement is brought about by the contraction and relaxation of muscles. The two suckers serve for attachment during movement on a substratum.
Swimming movement: Leeches swim very actively and perform undulating movements in water.

11. Name two layered protective covering of human heart.

Two layered protective covering of human heart is Pericardium.

12. What is the shape of RBC in human blood?

RBCs of human blood are biconcave or disc-shaped.

13. What causes the opening and closing of guard cells of stomata during transpiration?

The opening and closing of the stomata is due to the change in turgidity of the guard cells.
When turgidity increases within the two guard cells stoma opens.
When the guard cells lose water, it becomes flaccid and the stoma closes.

14. What is cohesion?

The force of attraction between molecules of water is called cohesion.

15. Why is the circulation in man referred to as double circulation?

When the blood circulates twice through the heart in one complete cycle, it is called double circulation.

16. What are heart sounds? How are they produced?

The rhythmic closure and opening of the valves cause the sound of the heart.

The first sound LUBB is of longer duration and is produced by the closure of the tricuspid and bicuspid valves after the beginning of ventricular systole.
The second sound DUPP is of a shorter duration and produced by the closure of semilunar valves at the end of ventricular systole.

17. Differentiate between systemic circulation and pulmonary circulation.

No	Systemic Circulation	Pulmonary Circulation
1	It occurs between the heart and the entire body.	It occurs between the heart and the lungs.
2	It carries oxygenated blood from the heart around the body then carries the deoxygenated blood from the body back to the heart.	It carries deoxygenated blood from the heart to the lungs and oxygenated blood from lungs to the heart.

18. Differentiate between systole and diastole. Explain the conduction of heart beat.

I. Differences between Systole and Diastole

No	Systole	Diastole
1	It is the contraction of atrium and ventricles.	It is the relaxation of atrium and ventricles.
2	Due to systole, the auricles and ventricles push the blood out of heart.	Due to diastole, the auricles are filled with blood.
3	Atrial systole lasts about 0.1 seconds. Ventricular systole lasts about 0.3 seconds.	Ventricular diastole lasts about 0.4 seconds.

II. The conduction of heart beat

Sino-atrial node acts as the 'pacemaker' of the heart because it is capable of initiating impulse which can stimulate the heart muscles to contract.
The impulse from the sinoatrial node spreads as a wave of contraction over the right and left atrial wall pushing the blood through the atrioventricular valves into the ventricles.
The wave of contraction from SA node reaches the atrioventricular (AV) node which is stimulated to emit an impulse of contraction spreading to the ventricular muscle via the atrioventricular bundle and the Purkinje fibres.

19. Define stimulus.

'Stimulus' refers to the changes in the environmental condition that are detected by receptors present in the body.

20. Name the parts of the hind brain.

Hindbrain is formed of three parts:

Cerebellum
Pons
Medulla oblongata

21. Define reflex arc.

A reflex action is any response that occurs automatically without consciousness. The pathway taken by nerve impulse to accomplish reflex action is called reflex arc.

22. Differentiate between Voluntary and involuntary actions.

No	Voluntary Actions	Involuntary Actions
1	The Voluntary actions are under the control of our will. e.g Eating, Locomotion etc.	Involuntary actions are not under our control. e.g Breathing, Heart beat etc.
2	It is controlled by the brain.	It is controlled by the spinal cord.
3	All voluntary actions result in a muscular action.	Involuntary actions result in a muscular action or secretion from some gland.

23. Differentiate between Medullated and non-Medullated nerve fibre.

No	Medullated nerve fibre	Non-Medullated nerve fibre
1	The axon is covered with myelin sheath.	The axon is not covered by myelin sheath.
2	They form the white matter of the brain.	They form the grey matter of the brain.
3	They are also known as Myelinated nerve fibre.	They are also known as Non-myelinated nerve fibre.

24. With a neat labelled diagram explain the structure of a neuron.

A neuron typically consists of three basic parts: Cyton, Dendrites and Axon.

Cyton:

Cyton is also called cell body or perikaryon.
It has a central nucleus with abundant cytoplasm called neuroplasm.
The cytoplasm has large granular body called Nissl's granules and the other cell organelles like mitochondria, ribosomes, lysosomes, and endoplasmic reticulum.
Neurons do not have the ability to divide.
Several neurofibrils are present in the cytoplasm that helps in transmission of nerve impulses to and from the cell body.

Dendrites:

These are the numerous branched cytoplasmic processes that project from the surface of the cell body. They conduct nerve impulses towards the cyton.
The branched projections increase the surface area for receiving the signals from other nerve cells.

Axon:

The axon is a single, elongated, slender projection.
The end of axon terminates as fine branches which terminate into knob-like swellings called synaptic knob.
The plasma membrane of axon is called axolemma, while the cytoplasm is called axoplasm. It carries impulses away from the cyton.
The axons may be covered by a protective sheath called myelin sheath which is further covered by a layer of Schwann cells called neurilemma.
Myelin sheath breaks at intervals by depressions called Nodes of Ranvier.
The region between the nodes is called as internode.
Myelin sheath acts as insulator and ensures rapid transmission of nerve impulses.

25. Illustrate the structure and functions of brain.

I. Fore brain

No	Structure	Functions
1	Cerebrum is the largest portion forming nearly two-third of the brain. It is longitudinally divided into two halves as right and left cerebral hemispheres. Outer portion is grey matter (cerebral cortex); inner portion is white matter (cerebral medulla).	The cerebrum is responsible for thinking, intelligence, consciousness, memory, imagination, reasoning and willpower.
2	Thalamus present in cerebral medulla.	Acts as relay station.
3	Hypothalamus lies at the base of the thalamus.	Temperature control, thirst, hunger, urination, important link between nervous system and endocrine glands.

II. Mid brain

No	Structure	Functions
1	Corpora quadrigemina is the dorsal portion of the mid brain consisting of four rounded bodies.	It controls visual and auditory (hearing) reflexes.

III. Hind brain

No	Structure	Functions
1	Cerebellum is second largest part of the brain formed of two large sized hemispheres and middle vermis.	It coordinates voluntary movements and also maintains body balance.
2	Pons is a bridge of nerve fibres that connects the lobes of cerebellum.	It relays signals between the cerebellum, spinal cord, midbrain and cerebrum. It controls respiration and sleep cycle.
3	Medulla oblongata is the posterior-most part of the brain that connects spinal cord and various parts of brain.	It has cardiac centres, respiratory centres, and vasomotor centres to control heartbeat, respiration and contractions of blood vessels respectively. It also regulates vomiting and salivation.

26. Which hormone induces parthenocarpy in tomatoes?

Gibberellins hormone induces parthenocarpy in tomatoes.

27. Which hormone is secreted during emergency situation in man?

Adrenaline is secreted during emergency situation in man.

28. What are synthetic auxins? Give examples.

Artificially synthesized auxins that have properties like auxins are called as synthetic auxins. Example: 2, 4-D (2, 4-Dichlorophenoxy Acetic Acid).

29. What is bolting? How can it be induced artificially?

Bolting: Treatment of rosette plants with gibberellin induces sudden shoot elongation followed by flowering. This is called bolting. It is induced by artificial treatment with plant hormone gibberellin. It causes stem elongation in plants under normal condition.

30. What are chemical messengers?

Hormones are powerful messengers that control and coordinate essential processes such as growth, metabolism and fertility by carrying messages from endocrine glands to target cells and tissues.

31. Write the differences between endocrine and exocrine gland.

No	Endocrine gland	Exocrine gland
1	They secrete hormones.	They secrete enzymes, saliva, and milk.
2	They are ductless glands.	They may have or may not have ducts.
3	They are transported through blood stream.	They are transported through ducts or tubes.
4	They control long-term activities.	They control short-term activities.
5	Ex: Pituitary, Thyroid, Adrenal, etc.	Ex: Salivary, Gastric and Sweat glands.

32. What is the role of parathormone?

Role of parathormone:

The parathormone regulates calcium and phosphorus metabolism in the body.
They act on bone, kidney and intestine to maintain blood calcium levels.

33. Why are thyroid hormones referred as personality hormone?

As thyroid hormones (Triiodothyronine (T₃) and Tetraiodothyronine (T₄) or Thyroxine) are essential for normal physical, mental and personality development, they are also known as personality hormone.

34. Write the physiological effects of gibberellins.

Physiological effects of Gibberellins:

Application of gibberellins on plants stimulates extraordinary elongation of internode (e.g., Corn and Pea).
Treatment of rosette plants with gibberellin induces sudden shoot elongation followed by flowering. This is called bolting.
Gibberellins promote the production of male flowers in monoecious plants (Cucurbits).
Gibberellins break dormancy of potato tubers.
Gibberellins are more efficient than auxins in inducing the formation of seedless fruit – Parthenocarpic fruits (Development of fruits without fertilization) e.g., Tomato.

35. Where are estrogens produced? What is the role of estrogens in the human body?

Estrogens are produced by the Graafian follicles of the ovary.

Functions of estrogens:

It brings about the changes that occur during puberty.
It initiates the process of oogenesis.
It stimulates the maturation of ovarian follicles in the ovary.
It promotes the development of secondary sexual characters (breast development, high-pitched voice etc.).

36. Name the hormone responsible for the vigorous contractions of the uterine muscles.

Oxytocin from the posterior pituitary stimulates the uterine contractions and provides force to expel the baby from the uterus, causing birth.

37. What is the enzyme present in acrosome of sperm?

Acrosome contains hyaluronidase, an enzyme that helps the sperm to enter the ovum during fertilization.

38. How does Binary fission differ from multiple fission?

No	Binary Fission	Multiple Fission
1	A single parent cell divides into two daughter cells.	A single parent cell divides into many daughter cells.
2	It occurs during favourable conditions (e.g., Amoeba).	It occurs during unfavourable conditions (e.g., Plasmodium).

39. Define triple fusion.

The fusion of second sperm (n) with secondary nucleus (2n) is known as triple fusion. As the result of triple fusion endosperm nucleus is formed.

Second sperm (n) + Secondary nucleus (2n) = Endosperm nucleus (3n)

40. What is colostrum? How milk production is hormonally regulated?

The first fluid which is released from the mammary gland after childbirth is called colostrum.

Milk production from alveoli of mammary glands is stimulated by prolactin secreted from the anterior pituitary. The ejection of milk is stimulated by posterior pituitary hormone oxytocin.

41. Why are the human testes located outside the abdominal cavity? Name the pouch in which they are present.

Human testes responsible for formation of sperms (Spermatogenesis) need slightly lower temperature than the normal body temperature for this function.

So human testes are located outside the abdominal cavity in a sac-like structure called scrotum.

42. Why did Mendel select pea plant for his experiments?

Mendel chose the pea plant as it was advantageous for experimental work in many aspects:

It is naturally self-pollinating and so is very easy to raise pure breeding individuals.
It has a short life span as it is an annual and so it was possible to follow several generations.
It is easy to cross-pollinate.
It has deeply defined contrasting characters.
The flowers are bisexual.

43. What do you understand by the term phenotype and genotype?

Phenotype: External expression of a particular trait is known as phenotype.
Genotype: Genetic expression of an organism is known as genotype.

44. What are allosomes?

Allosomes are chromosomes which are responsible for determining the sex of an individual. They are also called as sex chromosomes or heterochromosomes. The 23^rd pair of chromosomes in human beings is an allosome.

45. What are Okazaki fragments?

During the replication of a DNA molecule:

In one strand, the daughter strand is synthesized as a continuous strand which is called leading strand.
In the other strand, short segments of DNA are synthesized. This strand is called lagging strand.
These short segments of DNA are called Okazaki fragments.
The fragments are joined together by the enzyme, DNA ligase.

46. Explain the structure of a chromosome. (Refer Book for Diagram).

The chromosomes are thin, long and thread-like structures consisting of two identical strands called sister chromatids.
They are held together by the centromere.
Each chromatid is made up of spirally coiled thin structure called chromonema.
The chromonema has a number of bead-like structures along its length which are called chromomeres.
The chromosomes are made up of DNA, RNA, chromosomal proteins (histones and non-histones) and certain metallic ions.
These proteins provide structural support to the chromosome.

47. Define Ethnobotany and write its importance.

Ethnobotany is the study of a region's plants and their practical uses through the traditional knowledge of the local culture of people.

Importance of Ethnobotany:

It provides traditional uses of plants.
It gives information about certain unknown and known useful plants.
The ethnomedicinal data will serve as a useful source of information for chemists, pharmacologists and practitioners of herbal medicine.
Tribal communities utilize ethnomedicinal plant parts like bark, stem, roots, leaves, flower buds, flowers, fruits, seeds, oils, resins, dyes, gum for the treatment of diseases like diarrhea, fever, headache, diabetes, jaundice, snakebites, leprosy, etc.

48. How do you differentiate homologous organs from analogous organs?

S.No	Homologous Organ	Analogous Organ
1	They have inherited from common ancestors with similar developmental pattern in embryos.	They have different origin with different developmental patterns.
2	Homologous organs look dissimilar and are adapted for different functions.	The analogous organs look similar and perform similar functions.
3	Example 1: Forelimb of a frog and man seem to be built from the same basic design of bones but they perform different functions.	Example 1: Wings of birds and bats look similar. But in birds wings are covered by feathers all along the arm, whereas the wings of bats are skin folds stretched between elongated fingers.
4	Example 2: A human hand, a front leg of a cat, flipper of a whale and a bat's wing look dissimilar and adapted for different functions.	Example 2: Penguins and fish both have fin-like structures to swim in aquatic environments. These locomotory organs have different origin but look similar and perform similar functions.

49. Define genetic engineering.

Genetic engineering is the manipulation and transfer of genes from one organism to other organisms to create a new DNA called recombinant DNA (rDNA). Genetic engineering is also called recombinant DNA technology.

50. Name the types of stem cells.

Embryonic stem cells: They can be extracted and cultured from early embryos.
Adult stem cells or somatic stem cells: They are found in neonatal (newborn) and adults.

51. What are transgenic organisms?

Plants or animals expressing a modified endogenous gene or a foreign gene are known as transgenic organisms.

52. State the importance of Biofertiliser.

Biofertiliser is used to develop crop plants enriched with high levels of desirable nutrients like vitamins, proteins, and minerals.

53. Distinguish between:

a. Somatic gene therapy and germ line gene therapy

S.No	Somatic Gene Therapy	Germ Line Gene Therapy
1	It is the replacement of defective gene in somatic cells.	It is the replacement of defective gene in germ cells (sperm and egg).
2	Correction of genetic defects is beneficial to the patient. It may not be carried to the next generation.	It will be inherited and beneficial to next generations.

b. Undifferentiated cells and differentiated cells

S.No	Undifferentiated cells	Differentiated cells
1	They are unspecialized mass of cells. These cells could still become any kind of cell that the body needs.	They become specialized cells for performing specific functions.
2	Example: Cells in early embryos are undifferentiated. They multiply without being specialized yet.	Example: Liver cells, blood cells, neurons, muscle cells, skin cells, etc.

54. State the applications of DNA fingerprinting technique.

Applications of DNA Fingerprinting:

DNA fingerprinting technique is widely used in forensic applications like crime investigation such as identifying the culprit.
It is also used for paternity testing in case of disputes.
It helps in the study of genetic diversity of populations, evolution, and speciation.

55. Differentiate between outbreeding and inbreeding.

S.No	Outbreeding	Inbreeding
1	It is the breeding of unrelated animals.	It refers to the mating of closely related animals within the same breed.
2	The hybrids are stronger and more vigorous than their parents.	It helps in the accumulation of superior genes and elimination of undesirable genes.
3	Cross between two different species with desirable economic features is mated. Male donkey + Female horse = Mule	Superior males and superior females of the same breed are identified and mated in pairs. Bikaneri (Magra) ewes + Australian Merino rams = Hisardale sheep

56. What are psychotropic drugs?

The drugs which act on the brain and alter behavior, consciousness, power of thinking, and perception are called Psychotropic drugs. They are also called Mood-altering drugs.

57. What is Metastasis?

The cancerous cells migrate to distant parts of the body and affect new tissues; this process is called Metastasis.

58. Differentiate between Type-1 and Type-2 Diabetes mellitus.

S.No	Type 1 Diabetes mellitus	Type 2 Diabetes mellitus
1	People with Type 1 Diabetes do not produce insulin in the pancreas.	People with Type 2 Diabetes do not respond effectively to insulin.
2	The immune system destroys insulin-producing beta cells in the pancreas.	Target cells are insulin resistant; the pancreas produces insulin but cannot use it effectively.
3	Cannot be controlled without taking insulin.	Possible to treat initially through diet, exercise, or oral medication.

59. What precautions can be taken for preventing heart disease?

Diet management: Reduction in calorie intake, low saturated fat and cholesterol-rich foods, low carbohydrates and common salt. Diet rich in polyunsaturated fatty acids is essential. Increased intake of fibre, fruits, vegetables, proteins, minerals, and vitamins.
Physical activity: Regular exercise, walking, and yoga are essential for maintaining body weight.
Avoid Addictive substances: Alcohol consumption, psychotropic drugs, and smoking should be strictly avoided.

60. What are the agents of soil erosion?

Agents of soil erosion:

High velocity of wind
Flowing water
Landslides
Overgrazing by cattle
Human activities (deforestation, mining, intensive agriculture)

61. Why fossil fuels are to be conserved?

Fossil fuels are available in limited amounts in nature and the formation of these fossil fuels is an extremely slow process taking millions of years for renewal. Hence, fossil fuels must be conserved.

62. How are e-wastes generated?

E-wastes are generated from spoiled, outdated, and non-repairable electrical and electronic devices.

63. What is the importance of rainwater harvesting?

Importance of rainwater harvesting:

Overcomes the rapid depletion of groundwater levels.
Helps meet the increasing demand for water.
Reduces urban flooding and soil erosion.
Water recharged into the ground remains protected from contamination and can be used for drinking purposes.

64. What are the advantages of using biogas?

Advantages of biogas:

It burns without smoke and therefore causes minimal pollution.
Provides an excellent way to safely dispose of organic bio-wastes and sewage.
The spent slurry is an excellent manure rich in nitrogen and phosphorus.
It is safe, clean, and convenient to use.
Reduces direct emission of greenhouse gases into the atmosphere.

65. What are the consequences of deforestation?

Deforestation leads to major ecological problems such as:

Frequent floods and droughts
Severe soil erosion
Loss of wildlife habitat and extinction of vulnerable species
Imbalance in biogeochemical cycles
Alteration of regional climatic conditions
Desertification

66. How will you prevent soil erosion?

Management of Soil Erosion:

Retain vegetation cover so that the topsoil is not directly exposed.
Cattle overgrazing should be prevented.
Crop rotation and balanced soil management to improve organic content.
Runoff water should be conserved in watershed catchments.
Reforestation, contour bunding, terracing, and contour ploughing on slopes.
Wind speed should be checked by planting shelter belts of trees.

67. Enumerate the importance of forest.

Forests are an important component of our environment, dominated by trees, shrubs, and climbers, providing natural habitats for wild animals.
They contribute greatly to the economic development of our country.
Forests provide essential renewable resources like timber, wood, food, fodder, fibres, and medicinal plants.
They act as massive carbon sinks, regulate local climate, increase rainfall, and curb global warming.
Forests prevent natural hazards like floods and landslides, protect watersheds, and preserve water resources.
They play a vital, irreplaceable role in maintaining overall ecological balance.