ICSE Class 10 Biology — 2023 Paper

X chromosome

Reason — Human ovum have 'XX' as pair of sex chromosomes.

Flowers

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

Semilunar valves close

Reason — 'Dup' sound is produced at the beginning of ventricular diastole when the semilunar valve at the root of aorta and pulmonary artery close.

Tap water

Reason — When plasmolysed cell is placed in Tap water (hypotonic solution), the cell absorbs water and becomes normal. This is known as deplasmolysis.

Glucagon

Reason — Alpha cell of islet of Langerhans in Pancreas secrete glucagon. It stimulates liver to convert glycogen into glucose.

Sperms

Reason — The gametes (sperm or ovum) are formed as a result of meiosis in which the number of chromosomes are halved.

120 days

Reason — The life span of an RBC is 120 days.

Demography

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

Urochrome

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

Accelerates heartbeat

Reason — The sympathetic nervous system prepares the body for emergency situations.

Grana of chloroplast

Reason — The site of light reaction in the cells of a green leaf is grana of chloroplast which has chlorophyll.

Cobalt chloride paper

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

Lens and Retina

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

Hepatic artery

Reason — Oxygenated blood to liver is supplied by hepatic artery.

DNA is synthesised

Reason — During the synthesis phase (S phase) of the cell cycle, the primary focus is on the synthesis of DNA. This phase is when the cell replicates its DNA in preparation for cell division.

(i) Centriole

(ii) Hemophilia

(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, Syringes — Bio-medical wastes

(b) Odd one : Effluents
Dust, Smoke, Carbon monoxide — Air pollutant

(c) Odd one : Uterus
Urethra, Urinary bladder, Ureter — Parts of Excretory System

(d) Odd one : Telophase
Menstrual phase, Follicular phase, Luteal phase — Menstrual cycle

(e) Odd one : Cochlea
Malleus, Incus, Stapes — Ear ossicles

(a) Thyroid gland → Infront of neck below larynx.

(b) Dura mater → The outermost membrane covering the brain directly under skull.

(c) Amniotic fluid → In the space between the amnion and the embryo.

(d) Papillary muscles → Lower portion of the interior walls of the ventricles.

(e) Islets of Langerhans → Pancreas.

Balanced chemical equation representing the process of photosynthesis is given below:

$6\text{CO}_2 + 12\text{H}_2\text{O} \xrightarrow[\text{chlorophyll}]{\text{light energy}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{H}_2\text{O} + 6\text{O}_2 \uparrow$

Two functions of blood are:

1. Transport of digested food (in the form of simple sugars like glucose, amino acids, vitamins, mineral salts, etc.) 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 in agricultural fields leads to accumulation of unused chemicals in soil. The soil becomes either acidic or basic, making the soil unfit for cultivation. Also the beneficial microorganisms present in the soil are killed due to chemicals and disturbed ph of soil. Therefore, excessive use of fertilizers in agricultural fields reduces the yield of crops.

(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:

1. Tubectomy
2. 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

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

1. Sunken stomata : The stomata may be sunken or covered by hairs.
2. 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.

Semicircular canals help to keep the dynamic balance of the body while utriculus helps in maintaining static balance of the body.

(a) Presence of chlorophyll is necessary for photosynthesis.

(b) The plant is kept in dark for 24 hours to 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,Rr will be red flowering and rr will be 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: