ICSE Class 10 Biology Solved Paper 2023

(a) X chromosome

Explanation:

Human ova have XX as the pair of sex chromosomes.

(d) Flowers

Explanation:

Biodegradable waste refers to organic materials that can be broken down naturally by microorganisms and environmental processes. Flowers are organic waste that can decompose over time, whereas metal cans, e-waste and plastic are non-biodegradable wastes.

(c) Semilunar valves close

Explanation:

The ‘Dup’ sound is produced at the beginning of ventricular diastole when the semilunar valves at the roots of the aorta and pulmonary artery close.

(b) Tap water

Explanation:

When a plasmolysed cell is placed in tap water, which is hypotonic, the cell absorbs water and becomes normal. This is known as deplasmolysis.

(c) Glucagon

Explanation:

Alpha cells of the islets of Langerhans in the pancreas secrete glucagon. It stimulates the liver to convert glycogen into glucose.

(d) Sperms

Explanation:

The gametes, sperm or ovum, are formed as a result of meiosis in which the number of chromosomes is halved.

(a) 120 days

Explanation:

The life span of an RBC is 120 days.

(b) Demography

Explanation:

Demography is the term given to the statistical study of human population.

(c) Urochrome

Explanation:

Urochrome is the pigment responsible for the pale yellow colour of normal human urine.

(b) Grana of chloroplast

Explanation:

The site of the light reaction in the cells of a green leaf is the grana of chloroplast, which contain chlorophyll.

(d) Cobalt chloride paper

Explanation:

Cobalt chloride paper turns from blue to pink when exposed to moisture. Hence, it is used to demonstrate unequal transpiration in a dicot leaf.

(b) Lens and Retina

Explanation:

Vitreous humour is present between the lens and retina. It provides nutrition to the eye.

(a) Hepatic artery

Explanation:

Oxygenated blood to the liver is supplied by the hepatic artery.

(c) DNA is synthesised

Explanation:

During the synthesis phase, or S phase, of the cell cycle, DNA is synthesised. The cell replicates its DNA in preparation for cell division.

(i) Centriole

(ii) Haemophilia

(iii) Menopause

(iv) Lenticels

(v) Ethylene

(a) Cabbage → Rabbit → Snake → Hawk

(b) Soil water → Root hair → Cortical cells → Xylem

(c) Receptor → Spinal Cord → Effector → Response

(d) Conjunctiva → Cornea → Lens → Fovea

(e) Testis → Epididymis → Sperm duct → Urethra

(a) Odd one: Pesticides

Used bandages, face masks and syringes belong to the category of bio-medical wastes.

(b) Odd one: Effluents

Dust, smoke and carbon monoxide are air pollutants.

(c) Odd one: Uterus

Urethra, urinary bladder and ureter are parts of the excretory system.

(d) Odd one: Telophase

Menstrual phase, follicular phase and luteal phase are phases of the menstrual cycle.

(e) Odd one: Cochlea

Malleus, incus and stapes are ear ossicles.

The balanced chemical equation representing photosynthesis is:

6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂↑

The reaction takes place in the presence of light energy and chlorophyll.

Two functions of blood are:

1. Transport of digested food, such as glucose, amino acids, vitamins and mineral salts, from the alimentary canal to the tissues.
2. Transport of oxygen from the lungs to the tissues by means of haemoglobin present in red blood cells.

Excessive use of fertilizers increases the concentration of mineral salts in the soil, making the soil solution hypertonic in relation to the root cells. Water then moves out of the root cells by exosmosis, causing plasmolysis and reducing water absorption. This adversely affects plant growth and reduces crop yield.

(a) Phototropism

(b) Auxin

(c) Shoots show positive phototropism whereas, roots show positive geotropism.

DNA — Deoxyribonucleic acid.

Active transport is the passage of a substance (salt or ion) from its lower to higher concentration through a living cell membrane using energy from the cell.

Adenine pairs with thymine with two hydrogen bonds.

Cytosine pairs with Guanine with three hydrogen bonds.

Law of Segregation (also called the law of purity of gametes) — The two members of a pair of factors separate during the formation of gametes. They do not blend but segregate or separate into different gametes. The gametes combine together by random fusion at the time of zygote formation.

Labelled diagram of a human sperm is shown below:

Population density is the number of individuals per square kilometre (km²) at any given time.

The two surgical methods of population control are:

• Tubectomy
• Vasectomy

Two factors responsible for population explosion in India are:

1. Desire for a male child.
2. Illiteracy and lack of awareness about birth control measures.

Two resources which come under pressure due to rising population are:

1. Water
2. Land

(a) Global warming

(b) Green house effect due to accumulation of greenhouse gases like Carbon dioxide (CO₂) and Methane (CH₄) in the atmosphere.

(c) To prevent global warming, use of fossil fuels should be minimized and renewable energy sources should be adopted rapidly. Deforestation should be stopped and more trees should be planted.

Transpiration is the loss of water in the form of water vapour from the aerial parts (leaves and stem) of the plant.

• Sunken stomata: The stomata may be sunken or covered by hairs.
• Narrow leaves: They have reduced surface area and hence reduced transpiration.

Two functions of the human foetal placenta are:

1. Placenta provides the foetus with oxygen and nutrients.
2. Placenta also removes carbon dioxide and waste products of the foetus.

Testes are responsible for the production of male gametes i.e., sperms. The normal body temperature does not allow the maturation of the sperms. Being suspended outside the body cavity, the temperature in the scrotal sac is 2 to 3°C lower than that of the body which is the suitable temperature for the maturation of the sperms.

Below labelled diagram shows Malpighian Capsule:

Reflex action is an automatic/quick/immediate involuntary action in the body brought about by a stimulus.

The Bowman’s capsule and the proximal convoluted part of all the nephrons lie in the cortex of kidneys giving it a dotted appearance. Henle’s loops and collecting ducts lie in the renal medulla giving it a striped appearance.

The two functions of cerebellum are:

1. Maintains balance of the body.
2. Coordinates muscular activity.

(a) Presence of chlorophyll is necessary for photosynthesis.

(b) The plant is kept in dark for 24 hours to destarch the leaves.

(c) After conducting the starch test, the green leaf portion turns blue, indicating starch presence, confirming photosynthesis due to chlorophyll. Non-green parts lack chlorophyll, don’t photosynthesize, and show no starch-related colour change.

Mutation is a sudden change in one or more genes, or in the number or in the structure of chromosomes.

Phenotypic Ratio: 3 : 1

RR and Rr will be red flowering plants, while rr will be a white flowering plant.

Genotypic Ratio: 1 : 2 : 1

RR (dominant homozygous), Rr (dominant heterozygous), rr (recessive homozygous)

On a bright sunny day, the rate of transpiration is much higher than any other days. The leaves of certain plants roll up on a bright sunny day to reduce the exposed surface and thus reduce the rate of transpiration.

A semipermeable membrane is a membrane which allows the passage of molecules selectively. It allows a solvent such as water molecules to pass through it freely but prevents the passage of the solute (sugar or salt molecules in solution).

Cell membrane is the semi permeable membrane present in the plant cell.

(a) Ventricles are in contraction phase.

(b) Blood is passing into aorta and pulmonary artery through semilunar valves.

(c) Difference between Systole and Diastole: