............... is the result of inward movement of water molecules.
- Plasmolysis
- Flaccidity
- Exosmosis
- Deplasmolysis
Answer
Deplasmolysis
Reason — Deplasmolysis is the process where a plasmolysed cell (shrunken due to water loss) gains water through endosmosis, causing the cell membrane to return to its normal position close to the cell wall.
Which of the following is an example of a natural reflex?
- Sneezing
- Applying brakes
- Giving a hand signal
- Playing an instrument
Answer
Sneezing
Reason — Sneezing is a natural (inborn) reflex that occurs automatically in response to irritation in the nasal passages. It doesn’t require learning or conscious effort.
A newly married couple are expecting their first child. What is the probability of them having a daughter?
- 10%
- 50%
- 75%
- 100%
Answer
50%
Reason — A mother always gives an X chromosome, and the father can give either X or Y. If the father gives X, the child is a girl (XX). If he gives Y, the child is a boy (XY).
So, there's a 50% chance of having a daughter.
Assertion (A): Veins starting from the intestines do not open directly into the inferior vena cava.
Reason (R): They unite and enter the liver as hepatic portal vein.
- (A) is true and (R) is false.
- (A) is false and (R) is true.
- Both (A) and (R) are true.
- Both (A) and (R) are false.
Answer
Both (A) and (R) are true.
Reason — Veins from the intestines do not open directly into the inferior vena cava. Instead, they join to form the hepatic portal vein, which first carries nutrient-rich blood to the liver for processing before it enters the general circulation.
The structure absent in a nerve cell is:
- Nucleus
- Centrosome
- Cytoplasm
- Neurilemma
Answer
Centrosome
Reason — Nerve cell lack a centrosome, which is why neurons cannot divide.
The number of chromosomes in the somatic cells of a human body before mitosis and after mitosis is:
- 23, 23
- 26, 46
- 23, 46
- 46, 46
Answer
46, 46
Reason — Somatic cells are body cells and have a diploid number of chromosomes, which is 46 in humans. During mitosis, the cell divides to form two identical daughter cells, each with the same number of chromosomes as the parent cell. The number of chromosomes before and after mitosis remains 46.
The inorganic constituent of urine is:
- Ammonia
- Urea
- Creatinine
- Uric acid
Answer
Ammonia
Reason — Urea, uric acid, and creatinine are organic nitrogenous wastes. Ammonia is an inorganic compound. Although most ammonia is converted to urea in the liver, a small amount is excreted unchanged in urine.
Assertion (A): Darwin preferred pea plants for his experiments on genetics as it is a unisexual plant.
Reason (R): Pea plants are normally self-pollinated.
- (A) is true and (R) is false.
- (A) is false and (R) is true.
- Both (A) and (R) are true.
- Both (A) and (R) are false.
Answer
(A) is false and (R) is true.
Reason — It was Gregor Mendel, not Darwin, who conducted genetic experiments using pea plants. Also, pea plants are bisexual, they have both male and female reproductive organs in the same flower.
Anup participated in a marathon race and felt dehydrated by the end of the race. The human body has mechanisms to conserve water and prevent dehydration. Which part of the nephron is primarily responsible for the reabsorption of water to prevent dehydration?
- Glomerulus
- Proximal Convoluted Tubule
- Loop of Henle
- Distal Convoluted Tubule
(a) 3
(b) 2 and 3
(c) 1, 2 and 3
(d) 2, 3 and 4
Answer
2, 3 and 4
Reason — Water is mainly reabsorbed in the proximal convoluted tubule, loop of Henle, and distal convoluted tubule of the nephron to help the body save water and prevent dehydration. The glomerulus only filters blood, it doesn't reabsorb water.
Which of the following process occurs only in meiosis and NOT in mitosis:
- Chromosome duplication
- Crossing over
- Cytokinesis
- Chromosome alignment
Answer
Crossing over
Reason — Crossing over (exchange of genetic material between homologous chromosomes) occurs only in meiosis, increasing genetic variation.
Assertion (A): Blood flows from the left atrium to the left ventricle of the heart.
Reason (R): The tricuspid valve separates the left atrium from the left ventricle.
- (A) is true and (R) is false.
- (A) is false and (R) is true.
- Both (A) and (R) are true.
- Both (A) and (R) are false.
Answer
(A) is true and (R) is false.
Reason — The bicuspid (mitral) valve separates the left atrium and left ventricle, not the tricuspid valve. The tricuspid valve is between the right atrium and right ventricle.
Which adaptation is NOT associated with desert plants to minimise water loss through transpiration?
- Reduced number of stomata
- Thick, waxy cuticle
- Deep root systems
- Increased leaf surface area
Answer
Increased leaf surface area
Reason — Desert plants have small or fewer leaves to reduce water loss. Increasing leaf surface area would cause more water to evaporate, so they do not have this adaptation.
Assertion (A): Spraying of pesticides and insecticides can cause water pollution.
Reason (R): Pesticides and insecticides are non-biodegradable agricultural wastes.
- (A) is true and (R) is false.
- (A) is false and (R) is true.
- Both (A) and (R) are true.
- Both (A) and (R) are false.
Answer
Both (A) and (R) are true.
Reason — Pesticides and insecticides don’t break down easily and can wash into water sources, causing pollution.
The diagram given below represents a nephron. Ultrafiltration of blood occurs in:
- Bowman’s capsule
- Glomerulus
- Proximal Convoluted Tubule
- Loop of Henle
Answer
Glomerulus
Reason — Ultrafiltration happens in the glomerulus, where blood is filtered to form the filtrate that enters the nephron.
Which of the following statements are correct?
P — Night blindness is caused by the deficiency of Vitamin A.
Q — Utriculus gives dynamic balance to the body.
R — Neuron is a single cell.
S — Fossil fuels are inexhaustible sources of energy.
- Q and S
- R and S
- P and Q
- P and R
Answer
P and R
Reason
P is correct — Night blindness is caused by Vitamin A deficiency.
Q is incorrect — Utriculus helps in static balance, not dynamic.
R is correct — A neuron is a single nerve cell.
S is incorrect — Fossil fuels are exhaustible, not inexhaustible.
Name the following:
(a) The endocrinal cells which secrete testosterone.
(b) The fluid which surrounds the developing embryo.
(c) A national campaign in India which aims to eliminate open defecation.
(d) Hormone responsible for the bending of a plant shoot towards light.
(e) The sensory organ present in the Cochlea for hearing.
Answer
(a) Leydig cells
(b) Amniotic fluid
(c) Swachh Bharat Abhiyan
(d) Auxin
(e) Organ of Corti
Given below is an experiment to demonstrate the magnitude of transpiration in a dicot leaf. Read the information given below and fill in the blanks.
Transpiration is the process of loss of water as water vapour from the aerial parts of the plant. It is the essential driving force for the ascent of sap. Less than 1% of the water absorbed by the roots is used in photosynthesis and plant growth. The rest of the water is lost during transpiration.
Pieces of dried (a) ............... paper are fixed to the two surfaces of a leaf. The leaf should remain attached to the plant. The plant is exposed to bright sunlight for a few hours. The colour of the paper on the lower surface of the leaf turns (b) ............... faster than the one on the upper surface. This proves that more (c) ............... occurs from the (d) ............... surface of the leaf as it has a greater number of (e) ............... .
Answer
Pieces of dried (a) cobalt chloride paper are fixed to the two surfaces of a leaf. The leaf should remain attached to the plant. The plant is exposed to bright sunlight for a few hours. The colour of the paper on the lower surface of the leaf turns (b) pink faster than the one on the upper surface. This proves that more (c) transpiration occurs from the (d) lower surface of the leaf as it has a greater number of (e) stomata.
Arrange the terms in each group in the correct order. Write them in a logical sequence beginning with the term that is underlined.
(a) Follicular phase, Luteal phase, Menstrual phase, Ovulatory phase.
(b) Oval window, Auditory canal, Cochlea, Ear ossicles.
(c) Retina, Eyeball, Sclera, Choroid.
(d) Arterioles, Vein, Artery, Capillaries.
(e) Parturition, Implantation, Ovulation, Fertilisation.
Answer
(a) Menstrual phase, Follicular phase, Ovulatory phase, Luteal phase.
(b) Auditory canal, Ear ossicles, Oval window, Cochlea.
(c) Eyeball, Sclera, Choroid, Retina.
(d) Artery, Arterioles, Capillaries, Vein.
(e) Ovulation, Fertilisation, Implantation, Parturition.
Given below is a vertical section of the human brain. Match the structures marked (a) to (e) with their correct functions.
Example: (f) – 6. Transfer information from one cerebral hemisphere to another.
Answer
(a) → (5)
(b) → (3)
(c) → (4)
(d) → (2)
(e) → (1)
Explanation
(a) is Hypothalamus its function is to (5) Control body temperature and pituitary.
(b) is Medulla oblongata its function is to (3) Control the activities of the internal organs.
(c) is Thalamus its function is to (4) Relay pain and pressure impulse to cerebrum.
(d) is Cerebellum its function is to (2) Maintain body balance.
(e) is Cerebrum its function is the (1) Seat of intelligence.
Read the explanations given below and name the structures:
Example: A cord that connects the placenta with the foetus.
Answer: Umbilical cord
(a) The fibres which hold the lens of the eye in position.
(b) The cells of the islets of Langerhans that secrete the hormone glucagon.
(c) The part of the chloroplast where the light independent phase occurs.
(d) Cap like structure seen around the head of the human sperm.
(e) The glands located at the upper sideward portion of the orbit of eye.
Answer
(a) Suspensory ligaments
(b) Alpha cells
(c) Stroma
(d) Acrosome
(e) Lacrimal glands
Ram has protruding eyes and a high metabolic rate.
Name the hormone responsible for this condition.
Answer
Thyroxine
What are the two hormones secreted by corpus luteum?
Answer
The two hormones secreted by Corpus luteum are:
- Progesterone
- Oestrogen
What are phytohormones? Give an example of the growth retarding hormone.
Answer
Phytohormones are chemical substances produced in plants that regulate growth, development, and responses to stimuli.
Example of a growth-retarding hormone: Abscisic acid (ABA). It slows down growth and promotes dormancy in seeds and buds.
Distinguish between stoma and stroma.
Answer
| Stoma | Stroma |
|---|---|
| A tiny pore on the surface of a leaf | The fluid-filled space inside a chloroplast |
| Found mostly on the lower epidermis of leaves | Found inside chloroplasts, surrounding the grana |
| Regulates gas exchange and transpiration | Site of the light-independent (dark) reactions of photosynthesis |
Navya is a high school biology student who recently visited a local farm as part of a school project. She observed water droplets on the leaves of certain plants early in the morning as shown in the figure.
(a) Name the process observed.
(b) Explain the process mentioned in (a).
(c) Give the reason for the occurrence of the above-mentioned process.
Answer
(a) Guttation
(b) Guttation is the process by which water droplets are exuded from the edges or tips of leaves through special pores called hydathodes, usually during the early morning or at night.
(c) Guttation occurs when root pressure is high and transpiration is low, especially at night, pushing out extra water through special pores called hydathodes.
Explain the term Gestation.
Answer
Gestation is the period between fertilisation and birth during which the embryo develops inside the uterus of the mother. In humans, the gestation period is about 9 months (approximately 280 days).
Expand the following abbreviations:
(a) ACTH
(b) ABA
Answer
(a) ACTH - Adrenocorticotropic Hormone
(b) ABA - Abscisic Acid
A basement godown is stocked with bags of food grains. It is observed that the walls of the godown cracked after being flooded with rain water. Explain the phenomenon.
Answer
When rainwater flooded the godown, the dry food grains soaked up water due to imbibition and swelled.
The swollen grains pressed hard on the walls, creating high pressure, which caused the walls to crack.
Name the compound formed when Haemoglobin combines with:
(a) Carbon monoxide
(b) Oxygen
Answer
(a) When Haemoglobin combines with carbon monoxide, it forms Carboxyhaemoglobin.
(b) When Haemoglobin combines with oxygen, it forms Oxyhaemoglobin.
The Amazon rain forest is referred to as the ‘Lungs of the Earth’. It plays an important role in climate regulation through photosynthesis. However, this delicate ecosystem is facing threats from deforestation, climate change and human encroachment which can lead to irreversible environmental consequences.
(a) How does photosynthesis contribute to the Amazon rain forests’ reputation as the ‘Lungs of the Earth’?
(b) In what way is the environment affected by deforestation?
(c) Name the pigment that captures the light energy during photosynthesis.
Answer
(a) Photosynthesis performed by the trees in the Amazon rain forest absorbs carbon dioxide and releases oxygen, which helps maintain atmospheric oxygen levels. This process supports life on Earth, earning it the name ‘Lungs of the Earth’.
(b) Deforestation reduces the number of trees, leading to less carbon dioxide being absorbed and more oxygen being depleted. It causes soil erosion, loss of biodiversity, and contributes to global warming and climate change.
(c) Chlorophyll.
Ravi cuts his finger while chopping vegetables. The bleeding from the injury did not stop immediately. What kind of genetic disorder is he suffering from?
Answer
Ravi is suffering from Haemophilia.
Given below is a set of terms.
Medullary Sheath, Myelin Sheath, Dendron, Meninges, Nissl’s granules
(a) Choose the odd term from the above list.
(b) Mention the category to which the other terms belong.
Answer
(a) The odd term is Meninges.
(b) The other terms belong to parts or structures of a nerve cell (neuron).
Human kidney is a complex organ. Kidneys receive blood through blood vessels which directly branch from the Aorta. Inside each kidney are tiny functional units which filter the blood.
(a) Name the blood vessels that supply blood to the kidneys.
(b) Which are the functional units that filter the blood?
Answer
(a) Renal arteries.
(b) Nephrons
Divya performed an experiment on photosynthesis. At the end of the experiment, she tested the experimental leaf for the presence of starch. During the starch test she first boiled the leaf in water and then in methylated spirit.
(a) Why did she boil the leaf in water?
(b) Mention the reason why she then boiled the leaf in methylated spirit.
Answer
(a) Divya boiled the leaf in water to kill the cells of the leaf and stop all chemical reactions.
(b) She then boiled the leaf in methylated spirit to remove chlorophyll, making the leaf decolorized so the starch test colour change is clearly visible.
Draw a neat, labelled diagram of a stomatal apparatus.
Answer
Below diagram shows the stomatal apparatus found in the epidermis of leaves with all the different parts labelled:
State the overall chemical equation for photosynthesis.
Answer
Name the structure responsible for each of the following:
(a) Conversion of mechanical sound waves to sound vibrations in the human ear.
(b) Maintaining equal air pressure on either side of the tympanum.
Answer
(a) Eardrum (Tympanic membrane)
(b) Eustachian tube
Given below are two statements which are incorrect. Rewrite the correct statements.
(a) Mendel proposed the theory of ‘Use and Disuse’ of organs.
(b) Meningitis is the inflammation of pericardium.
Answer
(a) Lamarck proposed the theory of ‘Use and Disuse’ of organs.
(b) Meningitis is the inflammation of meninges.
A colourblind child is born to a normal couple.
(a) Work out a cross to show how it is possible.
(b) Mention the sex of this child.
Answer
(b) The child is a boy (male), because only males have XY chromosomes, and the recessive allele on the X chromosome leads to colourblindness in males.
Mrs. Lata Mohan delivered twins – Lalit and Leela in the year 2014. The twins were not of the same gender but were born on the same day and around the same time.
(a) What kind of twins are Lalit and Leela?
(b) Are they monozygotic or dizygotic twins?
(c) Mention the sex chromosomes in each of the body cells of Lalit and Leela.
Answer
(a) Fraternal twins
(b) Dizygotic twins
(c) Lalit (boy): XY, Leela (girl): XX
Name the inner lining of the uterus.
Answer
Endometrium
Based on the image of the Neanderthal Man given below, describe any two characteristic features of this human species.
Answer
Two characteristic features of Neanderthal Man are:
- Cranial Capacity — Neanderthal Man had a cranial capacity of about 1450 cm3
- Development of Chin — Strong lower jaw with almost no chin.
State the location and function of the prostate gland present in the male reproductive system.
Answer
The prostate gland is located below the urinary bladder and surrounds the upper part of the urethra in the male reproductive system.
It produces a slightly alkaline fluid that forms part of the semen. It neutralises acid in female's vagina.
Viplav is a photographer. He finds that his vision gets blurred. This happens when he goes from taking pictures of faraway objects to reading text on his camera screen. He recalls learning about certain defects of the eyes during his school days.
(a) Name the defect of the eyes which Viplav is suffering from.
(b) Mention the type of lens that can be used to correct the above defect.
Answer
(a) Hyperopia.
(b) Convex lens.
Draw a neat labelled diagram of a nucleotide.
Answer
Explain the process of Phagocytosis.
Answer
Phagocytosis is the process in which most WBCs and particularly the neutrophils engulf particle-like solid substances, especially bacteria.
Give two examples of radiation pollutants.
Answer
- Radioactive waste from nuclear power plants
- X-rays from X-ray machine
The need to limit the size of the family is more vital today than ever before. Give two reasons.
Answer
- Overpopulation — A large population puts pressure on resources like food, water, and housing, leading to shortages and poor living conditions.
- Economic Stability — Smaller families can provide better education, healthcare, and opportunities for each child, improving overall quality of life.
The picture given below shows the athletes lined up at the starting line. The countdown begins and all are focused and alert waiting for the gunshot.
(a) Which hormone prepares the body in such a situation given above?
(b) Name the endocrine gland that secretes the hormone mentioned in (a).
Answer
(a) Adrenaline
(b) Adrenal gland (Adrenal medulla)
Madhu fell down while playing in the school playground and injured her knee. There was bleeding from the injured part but after some time a brown thick layer was formed on the injury to stop the bleeding.
(a) Name the solid structure labelled X that is formed on the injury.
(b) What is the enzyme that initiates the formation of X?
(c) Which mineral element is essential for the formation of X?
Answer
(a) Thrombus (Blood clot)
(b) Thrombokinase
(c) Calcium