Class 11 practice
Class 11 science questions.
Science questions for Class 11, at the level of students aged 15–17, each with its answer and a short explanation. Try each one before opening the answer.
Preeti crosses pure-breeding pea plants having round yellow seeds with pure-breeding plants having wrinkled green seeds. In the F2 generation obtained by self-pollinating the F1 plants, what proportion of the progeny displays a recombinant phenotype?
Level 3 of 5Show the answer
Answer: 6/16
In a dihybrid cross, the phenotypic ratio is 9:3:3:1. The recombinant phenotypes (round green and wrinkled yellow) account for 3/16 + 3/16 = 6/16 of the offspring.
In a standard Daniell cell, zinc and copper electrodes are placed in their respective sulphate solutions. What is the primary function of the potassium chloride salt bridge connecting both half-cells?
Level 3 of 5Show the answer
Answer: Maintaining electrical neutrality by ion migration
The salt bridge allows inert counter-ions to migrate into the half-cells. This balances accumulated charges, preventing polarization and completing the electrical circuit without mixing the solutions.
Ananya directs a narrow beam of white light through a triangular glass prism in her Bengaluru school laboratory. The light splits into a spectrum of colours on the opposite screen. Which physical property causes the violet component to deviate more than the red component?
Level 3 of 5Show the answer
Answer: Higher refractive index for shorter wavelengths
The refractive index of glass increases as wavelength decreases. Violet light has a shorter wavelength than red light, so it slows down more and undergoes greater deviation.
In a grassland ecosystem in Madhya Pradesh, grass captures 20,000 joules of solar energy through photosynthesis. According to Lindeman's ten percent law, how much energy is available to secondary consumers?
Level 3 of 5Show the answer
Answer: 200 joules
Only about 10% of energy transfers between successive trophic levels. Herbivores (primary consumers) receive 2,000 joules, leaving 200 joules available to secondary consumers.
An iron nail is placed inside an aqueous solution of copper sulphate in a chemistry laboratory. Over time, the solution turns pale green and a reddish coating forms on the nail. What type of reaction has occurred?
Level 3 of 5Show the answer
Answer: Displacement reaction
Iron is more reactive than copper, so it displaces copper from copper sulphate solution, forming iron(II) sulphate and depositing metallic copper.
A copper ring is suspended horizontally by a thread. When the north pole of a bar magnet is pushed vertically downward toward the ring, what magnetic polarity is induced on the upper face?
Level 3 of 5Show the answer
Answer: North pole
According to Lenz's law, induced currents oppose the change in magnetic flux producing them. The upper face develops a north pole to repel the approaching north pole of the magnet.
During eukaryotic DNA replication, one daughter strand is synthesized discontinuously because polymerases operate only in the 5'-to-3' direction. What are these short segments of newly synthesized DNA called?
Level 3 of 5Show the answer
Answer: Okazaki fragments
The lagging strand is synthesized discontinuously as short nucleotide segments known as Okazaki fragments. These segments are subsequently joined into a continuous strand by DNA ligase.
A communication satellite travels in a stable circular orbit around Earth at a constant speed. What provides the necessary centripetal force to keep the satellite in this circular path?
Level 3 of 5Show the answer
Answer: Earth's gravitational attraction
The gravitational force exerted by Earth acts perpendicularly to the satellite's tangential velocity, constantly pulling it towards the planet's centre and providing the requisite centripetal acceleration.
An artificial communications satellite orbits Earth in an elliptical trajectory. According to Kepler's second law of planetary motion, at which orbital position does the satellite travel at its maximum linear speed?
Level 3 of 5Show the answer
Answer: Perigee
Kepler's second law requires equal areas swept in equal times. Because the radial distance to Earth's centre is shortest at perigee, the satellite must move at its highest speed there.
Three identical resistors, each with a resistance of 6 ohms, are arranged such that two are connected in parallel. This pair is then connected in series with the third. What is the total equivalent resistance?
Level 3 of 5Show the answer
Answer: 9 ohms
The two parallel resistors yield an equivalent resistance of 3 ohms. Adding the 6-ohm series resistor gives a total equivalent resistance of 9 ohms.
During the electrolysis of a concentrated aqueous solution of sodium chloride using inert electrodes, which substance is discharged at the cathode?
Level 3 of 5Show the answer
Answer: Hydrogen gas
In an aqueous solution, hydrogen ions have a higher reduction potential than sodium ions. Consequently, hydrogen ions are preferentially reduced at the cathode to form hydrogen gas.
In a monohybrid cross between two pea plants heterozygous for round seeds (Rr), a botanist counts 400 offspring. How many of these offspring are expected to have a homozygous genotype for the seed shape trait?
Level 3 of 5Show the answer
Answer: 200
The genotypic ratio from an Rr x Rr cross is 1 RR : 2 Rr : 1 rr. Both RR and rr are homozygous, making up 50% of the progeny: 0.50 of 400 is 200.
- True or false?
Across the second period from left to right in the modern periodic table, the first ionisation enthalpy of oxygen exceeds that of nitrogen.
Level 3 of 5Show the answer
Answer: False
Nitrogen has an extra-stable, half-filled 2p subshell (2p³), whereas oxygen has four electrons (2p⁴). Consequently, removing an electron from nitrogen requires more energy than from oxygen.
- True or false?
The triple bond in a diatomic nitrogen molecule consists of one sigma bond and two pi bonds formed by the overlap of atomic p-orbitals.
Level 3 of 5Show the answer
Answer: True
The head-on overlap of axial p-orbitals forms one cylindrical sigma bond. The lateral overlap of the remaining mutually perpendicular pairs of p-orbitals generates two pi bonds.
- True or false?
In human genetics, the sperm cell determines the biological sex of the zygote because each male gamete carries either an X or a Y chromosome.
Level 3 of 5Show the answer
Answer: True
Ovum cells always carry an X chromosome. The fertilising sperm delivers either an X chromosome, producing an XX female, or a Y chromosome, producing an XY male.
- Fill in the blank.
The complex vascular tissue responsible for translocating soluble organic nutrients such as sucrose from photosynthetic leaves to other plant organs is the ___ (starts with 'P').
Level 3 of 5Show the answer
Answer: phloem
While xylem transports water and dissolved minerals upwards from the roots, phloem conducts synthesized food products bidirectionally throughout vascular plants via sieve tube elements and companion cells.
- Fill in the blank.
In the modern periodic table, an uncharged atom with atomic number 17 occupies group ___.
Level 3 of 5Show the answer
Answer: 17
Atomic number 17 corresponds to chlorine, which has seven valence electrons and belongs to group 17, the halogens.
- Fill in the blank.
The specialized microscopic apertures on aerial plant surfaces through which gaseous exchange and transpiration occur are known as ___ (first letter: s).
Level 3 of 5Show the answer
Answer: stomata
Stomata are pores bordered by specialized guard cells that open and close to regulate carbon dioxide intake and water vapour loss.
Which of the following waves is the odd one out?
Level 3 of 5Show the answer
Answer: Sound waves
Sound waves are longitudinal mechanical waves requiring a material medium. Light waves, radio waves, and X-rays are all transverse electromagnetic waves that can travel through a vacuum.
In human anatomy and physiology, which organ is the odd one out?
Level 3 of 5Show the answer
Answer: Salivary gland
The thyroid, pituitary, and adrenal glands are ductless endocrine glands that release hormones into circulation. The salivary gland is an exocrine gland.
These questions come from Ado’s question bank and are written with AI help. They are never used in ranked play, so practising them here can’t change anyone’s rank.
Spot a mistake? Tell us at hi@getado.app and we’ll fix it.
Last updated:
Science for other classes
Other subjects for Class 11
Olympiads for Class 11 · Science olympiad prep
A new set every morning
Ado’s daily brings fresh questions at this level every day, ranked only against students the same age. The Ado Rank it builds never resets.
For parents of students aged 6–17. Free to start, free to rank.