🔬 Science Question Papers (EM & TM) 1st Mid Term Test 2024 - Original Question Paper | Theni District | Mr. M. Senthilkumar (English Medium)

Solved: First Mid Term Test - 2024 | Standard X Science

FIRST MID TERM TEST - 2024

Standard X - SCIENCE (with Solutions)
Time: 1.30 hrs
Reg No.
Marks: 50

Part - I 10 x 1 = 10

I. Choose the correct answer:

1.
The unit of 'g' is \(ms^{-2}\), it can be also expressed as
  • a) \(cms^{-1}\)
  • b) \(Nkg^{-1}\)
  • c) \(Nm^{2}kg^{-1}\)
  • d) \(cm^{2}s^{-2}\)
Show Solution

Solution

Correct Answer: b) \(Nkg^{-1}\)

Explanation: According to Newton's second law of motion, Force (F) is the product of mass (m) and acceleration (a). For acceleration due to gravity (g), the formula is \( F = m \times g \). By rearranging the formula to solve for 'g', we get \( g = \frac{F}{m} \). The SI unit for Force is Newton (N) and for mass is kilogram (kg). Therefore, an alternative unit for 'g' is \( \frac{N}{kg} \), which is written as \(Nkg^{-1}\).

2.
Power of a lens is -4D, then its focal length is
  • a) 4 m
  • b) -40 m
  • c) -0.25 m
  • d) -2.5 m
Show Solution

Solution

Correct Answer: c) -0.25 m

Explanation: The power (P) of a lens is the reciprocal of its focal length (f) in meters. The formula is \( P = \frac{1}{f} \). To find the focal length, we rearrange the formula to \( f = \frac{1}{P} \). Given \( P = -4D \), the focal length is \( f = \frac{1}{-4} = -0.25 \) m.

3.
1 mole of any substance contains ____________ molecules.
  • a) \(6.023 \times 10^{23}\)
  • b) \(6.023 \times 10^{-23}\)
  • c) \(3.0115 \times 10^{23}\)
  • d) \(12.046 \times 10^{23}\)
Show Solution

Solution

Correct Answer: a) \(6.023 \times 10^{23}\)

Explanation: By definition, one mole of any substance contains a number of particles (atoms, molecules, or ions) equal to Avogadro's number. Avogadro's number is approximately \(6.023 \times 10^{23}\).

4.
Neon shows zero electron affinity due to
  • a) stable arrangement of neutrons
  • b) stable configurations of electrons
  • c) reduced size
  • d) Increased density
Show Solution

Solution

Correct Answer: b) stable configurations of electrons

Explanation: Neon is a noble gas with a completely filled valence electron shell (\(2s^2 2p^6\)). This stable electron configuration makes it very energetically unfavorable to add another electron. Therefore, it has a positive (or near-zero) electron affinity.

5.
Oxygen is produced at what point during photosynthesis?
  • a) when ATP is connected to ADP
  • b) when \(CO_2\) is fixed
  • c) when \(H_2O\) is splitted
  • d) all of these
Show Solution

Solution

Correct Answer: c) when \(H_2O\) is splitted

Explanation: During the light-dependent reactions of photosynthesis, light energy is used to split water molecules in a process called photolysis. This reaction releases electrons, protons (H\(^+\)), and oxygen gas (\(O_2\)) as a byproduct.

6.
In Leech, locomotion is performed by ____________.
  • a) Anterior sucker
  • b) Parapodia
  • c) Setae
  • d) Contraction and Relaxation of muscles
Show Solution

Solution

Correct Answer: d) Contraction and Relaxation of muscles

Explanation: Leeches move by a looping or crawling motion. This is achieved through the coordinated action of their longitudinal and circular muscles, which cause the body to lengthen and shorten. The suckers at both ends are used to anchor the body during this movement.

7.
Atrioventricular bundle was discovered by ____________.
  • a) William Harvey
  • b) His
  • c) Edward Jenner
  • d) None of the above
Show Solution

Solution

Correct Answer: b) His

Explanation: The atrioventricular bundle, a key part of the heart's electrical conduction system, was discovered in 1893 by the Swiss cardiologist Wilhelm His Jr. It is often referred to as the "Bundle of His".

8.
The wall of human heart is made of ____________.
  • a) endocardium
  • b) epicardium
  • c) myocardium
  • d) all the above
Show Solution

Solution

Correct Answer: d) all the above

Explanation: The wall of the human heart is composed of three distinct layers:

  • Epicardium: The outermost protective layer.
  • Myocardium: The middle, muscular layer responsible for pumping blood.
  • Endocardium: The innermost layer that lines the heart chambers.

9.
In Reflex action, the reflex arc is formed by ____________.
  • a) brain, spinal cord, muscle
  • b) receptor, muscle, spinal cord
  • c) muscle, receptor, brain
  • d) receptor, spinal cord, muscle
Show Solution

Solution

Correct Answer: d) receptor, spinal cord, muscle

Explanation: A reflex arc is the neural pathway for a reflex action. The basic sequence is: A stimulus is detected by a receptor, a nerve impulse travels along a sensory neuron to the spinal cord (which acts as the processing center), and then a motor neuron carries the impulse to an effector, such as a muscle, which responds.

10.
The eye defect "Presbyopia" can be corrected by ____________.
  • a) convex lens
  • b) concave lens
  • c) convex mirror
  • d) bifocal lenses
Show Solution

Solution

Correct Answer: d) bifocal lenses

Explanation: Presbyopia is an age-related condition where the eye's lens loses its flexibility, making it difficult to focus on near objects. Since affected individuals often also have other refractive errors (like myopia or hypermetropia), bifocal lenses are used. These lenses have two parts: the upper part for distant vision and the lower (convex) part for near vision.

Part - II 5 x 2 = 10

II. Answer any 5 questions. (Q.No.18 is compulsory)

11.
Define Inertia. Give its classification.
Show Solution

Solution

Definition: Inertia is the inherent property of a body to resist any change in its state of rest or state of uniform motion, unless it is acted upon by an external unbalanced force.

Classification of Inertia: Inertia is classified into three types:

  1. Inertia of rest: The resistance of a body to change its state of rest. (e.g., a passenger being pushed backward when a bus starts suddenly).
  2. Inertia of motion: The resistance of a body to change its state of uniform motion. (e.g., a passenger lurching forward when a moving bus stops suddenly).
  3. Inertia of direction: The resistance of a body to change its direction of motion. (e.g., passengers being pushed sideways when a bus takes a sharp turn).
12.
State Snell's Law.
Show Solution

Solution

Snell's Law states that:

The ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is a constant for a given pair of media. This constant is equal to the ratio of the refractive indices of the two media.

Mathematically, it is expressed as:

\[ \frac{\sin i}{\sin r} = \frac{\mu_2}{\mu_1} = \text{constant} \]

where:

  • \(i\) is the angle of incidence.
  • \(r\) is the angle of refraction.
  • \(\mu_1\) is the refractive index of the first medium.
  • \(\mu_2\) is the refractive index of the second medium.
13.
Differentiate Convex lens and Concave lens.
Show Solution

Solution

FeatureConvex LensConcave Lens
ShapeThicker at the center and thinner at the edges.Thinner at the center and thicker at the edges.
Action on LightIt is a converging lens; it bends parallel light rays inward to a focal point.It is a diverging lens; it spreads parallel light rays outward.
Focal LengthHas a positive focal length.Has a negative focal length.
Image FormedForms mostly real and inverted images (except for one case where it forms a virtual, erect image).Always forms virtual, erect, and diminished images.
Common UseUsed in magnifying glasses, cameras, and to correct hypermetropia (farsightedness).Used in peepholes, flashlights, and to correct myopia (nearsightedness).
14.
Give any two examples for hetero diatomic molecules.
Show Solution

Solution

Hetero diatomic molecules are molecules composed of two atoms of different elements. Two examples are:

  1. Hydrogen Chloride (HCl): A molecule made of one hydrogen atom and one chlorine atom.
  2. Carbon Monoxide (CO): A molecule made of one carbon atom and one oxygen atom.

Other examples include: Nitric Oxide (NO), Hydrogen Fluoride (HF).

15.
Why should the light-dependent reaction occur before the light-independent reaction?
Show Solution

Solution

The light-dependent reaction must occur before the light-independent reaction because it produces the necessary energy-carrying molecules (ATP and NADPH) required to power the second stage.

  • In the light-dependent reactions, light energy is captured and used to split water, producing oxygen, and converting ADP and NADP\(^+\) into ATP and NADPH.
  • In the light-independent reactions (Calvin Cycle), the chemical energy stored in ATP and NADPH is used to convert carbon dioxide (\(CO_2\)) into glucose (sugar).

Without the ATP and NADPH from the first stage, the second stage would have no energy to run, and photosynthesis would not be completed.

16.
State whether the statements are True or False. (Correct the false statement)
i) Anaerobic respiration produces more ATP than Aerobic respiration.
ii) Plants lose water by the process of transpiration.
Show Solution

Solution

i) False.
Corrected Statement: Aerobic respiration produces significantly more ATP (approximately 36-38 molecules) than Anaerobic respiration (only 2 molecules).

ii) True.

17.
Fill in the blanks.
i) Water enters into the root hair cell through __________ membrane.
ii) __________ is the longest cell in our body.
Show Solution

Solution

i) Water enters into the root hair cell through semi-permeable membrane (by osmosis).

ii) Nerve cell (or Neuron) is the longest cell in our body.

18.
Calculate the velocity of a moving body of mass 5 kg whose linear momentum is 2.5 kg \(ms^{-1}\).
Show Solution

Solution

Given:

  • Mass (m) = 5 kg
  • Linear momentum (p) = 2.5 kg \(ms^{-1}\)

Formula:

Linear momentum (p) is defined as the product of mass (m) and velocity (v).

\[ p = m \times v \]

Calculation:

To find the velocity (v), we rearrange the formula:

\[ v = \frac{p}{m} \]

Substitute the given values:

\[ v = \frac{2.5 \text{ kg } ms^{-1}}{5 \text{ kg}} \] \[ v = 0.5 \text{ } ms^{-1} \]

Answer: The velocity of the moving body is 0.5 \(ms^{-1}\).

Part - III 4 x 4 = 16

III. Answer any 4 questions. (Q.No.25 is compulsory)

19.
List out any five properties of light.
Show Solution

Solution

Here are five key properties of light:

  1. Rectilinear Propagation: Light travels in a straight line in a uniform medium. This is why shadows are formed.
  2. Reflection: Light bounces off a surface. This property is governed by the laws of reflection (angle of incidence equals angle of reflection).
  3. Refraction: Light bends when it passes from one medium to another (e.g., from air to water). This is due to the change in the speed of light.
  4. Speed: Light travels at a very high, finite speed. In a vacuum, its speed is approximately \(3 \times 10^8\) m/s.
  5. Dual Nature: Light exhibits properties of both a wave (showing diffraction and interference) and a particle (photoelectric effect). The particles of light are called photons.
20.
A is a silvery-white metal. A combines with \(O_2\) to form B at 800°C.
  1. The alloy of A is used in making the aircraft. Find A and B.
  2. What is Rust?
Show Solution

Solution

a) Find A and B:

  • The clues point to metal 'A' being Aluminium (Al). It is a silvery-white metal, and its alloys (like Duralumin) are extensively used in aircraft manufacturing due to their low density and high strength.
  • When Aluminium (A) combines with oxygen (\(O_2\)) at high temperatures, it forms Aluminium oxide (B).

So, A is Aluminium (Al) and B is Aluminium Oxide (\(Al_2O_3\)).

b) What is Rust?

Rust is the common term for a reddish-brown, flaky substance that forms on the surface of iron or its alloys when they are exposed to oxygen and moisture for a prolonged period. Chemically, rust is hydrated iron(III) oxide, with the general formula \( \text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} \).

21.
a) Match the following:
1. Amphicribal-Dracaena
2. Cambium-Fern
3. Amphivasal-Secondary growth
4. Xylem-Conduction of water

b) Why is the Sinoatrial node called the pacemaker of the heart?
Show Solution

Solution

a) Match the following:

1. Amphicribal→Fern
2. Cambium→Secondary growth
3. Amphivasal→Dracaena
4. Xylem→Conduction of water

b) Why is the Sinoatrial node called the pacemaker of the heart?

The Sinoatrial (SA) node is called the "pacemaker" of the heart because it has the ability to spontaneously generate electrical impulses at the highest rate within the heart's conduction system. These impulses initiate each heartbeat and set the rhythm (or pace) for the entire heart muscle. The impulses spread from the SA node across the atria, causing them to contract, and then travel to the rest of the conduction system to coordinate the contraction of the ventricles.

22.
i) Draw the structure of a neuron and label the parts. (2 marks)
ii) Write the reaction of photosynthesis.
Show Solution

Solution

i) Structure of a Neuron:

Below is a diagram of a typical neuron with its main parts labeled.

Dendrites Cell Body Nucleus Axon Myelin Sheath Node of Ranvier Axon Terminal

ii) Reaction of Photosynthesis:

The overall balanced chemical equation for photosynthesis is:

\[ 6CO_2 + 6H_2O \xrightarrow[\text{Chlorophyll}]{\text{Sunlight}} C_6H_{12}O_6 + 6O_2 \]

This translates to: Six molecules of Carbon Dioxide plus six molecules of Water, in the presence of sunlight and chlorophyll, produce one molecule of Glucose and six molecules of Oxygen.

23.
Enumerate the functions of blood.
Show Solution

Solution

Blood is a vital fluid that performs several critical functions in the body, which can be grouped into three main categories: transport, regulation, and protection.

  1. Transport:
    • Respiratory Gases: Transports oxygen from the lungs to the body tissues and carbon dioxide from the tissues back to the lungs.
    • Nutrients: Carries digested nutrients (like glucose, amino acids) from the digestive system to cells throughout the body.
    • Hormones: Transports hormones from endocrine glands to their target organs.
    • Waste Products: Carries metabolic wastes (like urea) from the cells to the kidneys and liver for excretion.
  2. Regulation:
    • Body Temperature: Helps regulate body temperature by absorbing and distributing heat throughout the body.
    • pH Level: Maintains the body's pH balance through buffer systems.
    • Water Balance: Regulates the water content of cells by managing fluid exchange.
  3. Protection:
    • Clotting: Platelets and clotting factors in the blood prevent excessive blood loss by forming clots at injury sites.
    • Immunity: White blood cells (leukocytes) defend the body against pathogens (bacteria, viruses), and antibodies in the plasma provide immunity.
24.
Differentiate between Aerobic and Anaerobic respiration.
Show Solution

Solution

Basis of DifferenceAerobic RespirationAnaerobic Respiration
Oxygen RequirementRequires oxygen.Does not require oxygen.
Location in CellOccurs in the cytoplasm (glycolysis) and mitochondria (Krebs cycle, ETC).Occurs only in the cytoplasm.
Breakdown of GlucoseComplete oxidation of glucose.Incomplete oxidation of glucose.
End ProductsCarbon dioxide (\(CO_2\)), water (\(H_2O\)), and ATP.Lactic acid (in animals) or ethanol and \(CO_2\) (in yeast), and ATP.
ATP YieldHigh energy yield (approx. 36-38 ATP molecules per glucose).Low energy yield (only 2 ATP molecules per glucose).
Process DurationA slower, more complex process involving multiple stages.A faster, simpler process.
25.
Calculate the number of moles in:
i) 27 g of Al
ii) \(1.5 \times 10^{23}\) molecules of \(NH_4Cl\)
Show Solution

Solution

i) 27 g of Al (Aluminium)

The number of moles is calculated using the formula:

\[ \text{Number of moles} = \frac{\text{Given mass}}{\text{Molar mass}} \]
  • Given mass of Al = 27 g
  • Atomic mass (molar mass) of Al = 27 g/mol
\[ \text{Number of moles} = \frac{27 \text{ g}}{27 \text{ g/mol}} = 1 \text{ mole} \]

Answer: There is 1 mole in 27 g of Aluminium.

ii) \(1.5 \times 10^{23}\) molecules of \(NH_4Cl\) (Ammonium Chloride)

The number of moles is calculated using Avogadro's number:

\[ \text{Number of moles} = \frac{\text{Number of molecules}}{\text{Avogadro's number}} \]
  • Given number of molecules = \(1.5 \times 10^{23}\)
  • Avogadro's number (\(N_A\)) = \(6.023 \times 10^{23}\) molecules/mol
\[ \text{Number of moles} = \frac{1.5 \times 10^{23}}{6.023 \times 10^{23}} \] \[ \text{Number of moles} \approx 0.249 \text{ moles} \]

Answer: There are approximately 0.25 moles in \(1.5 \times 10^{23}\) molecules of \(NH_4Cl\).

Part - IV 2 x 7 = 14

IV. Answer in detail.

26.
Deduce the equation for force using Newton's second law of motion.

(OR)

i) Give the salient features of modern atomic theory. (5 marks)
ii) Assertion and Reason - (2 marks)
  • Assertion: An uncleaned copper vessel is covered with a greenish layer.
  • Reason: Copper is not attacked by Alkali.
  1. A is wrong, R is correct
  2. A and R are correct, R does not explain A
Show Solution

Solution

Deduction of the Equation for Force (F = ma)

Newton's second law of motion provides the quantitative definition of force. The deduction is as follows:

  1. Statement of the Law: Newton's second law states that the force acting on a body is directly proportional to the rate of change of its linear momentum and the change in momentum takes place in the direction of the force.
  2. Mathematical Representation: Let a body of mass 'm' be moving with an initial velocity 'u'. When an external force 'F' is applied for a time interval 't', its velocity changes to 'v'.
    • Initial momentum (\(p_1\)) = mu
    • Final momentum (\(p_2\)) = mv
    • Change in momentum (\(\Delta p\)) = \(p_2 - p_1 = mv - mu = m(v - u)\)
  3. Rate of Change of Momentum: The rate of change of momentum is the change in momentum divided by time. \[ \text{Rate of change of momentum} = \frac{\Delta p}{t} = \frac{m(v-u)}{t} \]
  4. Applying the Law: According to Newton's second law, Force (F) is proportional to the rate of change of momentum. \[ F \propto \frac{m(v-u)}{t} \]
  5. Introducing Acceleration: We know that acceleration (a) is the rate of change of velocity, i.e., \( a = \frac{v-u}{t} \). Substituting this into the equation: \[ F \propto m \times a \]
  6. Forming the Equation: To turn the proportionality into an equation, we introduce a proportionality constant, 'k'. \[ F = kma \] The value of the constant 'k' is made equal to 1 by defining the unit of force. One unit of force is defined as the amount of force that produces an acceleration of \(1 \text{ ms}^{-2}\) in a body of mass 1 kg. Thus, k = 1.
  7. Final Equation: With k=1, the equation for force becomes: \[ F = ma \] This is the mathematical expression for force derived from Newton's second law.

(OR)

i) Salient Features of Modern Atomic Theory

The Modern Atomic Theory refines Dalton's original theory based on new discoveries. Its key features are:

  1. Atom is no longer indivisible: An atom is composed of subatomic particles: protons, neutrons, and electrons.
  2. Atoms of the same element may not be identical: The existence of isotopes (atoms of the same element with different mass numbers, e.g., \(^{12}\text{C}\) and \(^{14}\text{C}\)) proves that atoms of the same element can have different masses.
  3. Atoms of different elements may be identical in mass: The existence of isobars (atoms of different elements with the same mass number, e.g., \(^{40}\text{Ar}\) and \(^{40}\text{Ca}\)) shows that atoms of different elements can have the same mass.
  4. Atom is the smallest particle that takes part in a chemical reaction: While atoms are divisible, they remain the smallest unit that participates in chemical reactions.
  5. Atoms can be transmuted: Atoms of one element can be changed into atoms of another element through nuclear reactions (transmutation), which contradicts Dalton's idea of indestructible atoms.
  6. The mass of an atom can be converted into energy: This is explained by Einstein's equation, \(E=mc^2\), which links mass and energy.

ii) Assertion and Reason

  • Assertion (A): An uncleaned copper vessel is covered with a greenish layer.
    This statement is True. Copper reacts slowly with carbon dioxide and water vapor in the air to form a green layer of basic copper carbonate (\(CuCO_3 \cdot Cu(OH)_2\)).
  • Reason (R): Copper is not attacked by Alkali.
    This statement is also True. Copper is a relatively unreactive metal and does not react with alkalis like sodium hydroxide.

Analysis: While both statements are individually true, the reason (R) does not explain the assertion (A). The formation of the green layer is due to reaction with atmospheric gases, not because of its non-reactivity with alkalis.
Therefore, the correct option is:

b) A and R are correct, R does not explain A

27.
Describe and name three stages of cellular respiration that aerobic organisms use to obtain energy from glucose.

(OR)

i) List out the parasitic adaptations in Leech. (5 marks)
ii) Define 'Reflex arc'.
Show Solution

Solution

The Three Stages of Aerobic Cellular Respiration

Aerobic organisms extract energy from glucose in three main stages:

  1. Glycolysis ("Splitting of Sugar"):
    • Location: This stage occurs in the cytoplasm of the cell.
    • Process: A single molecule of glucose (a 6-carbon compound) is broken down into two molecules of pyruvic acid (a 3-carbon compound). This process does not require oxygen.
    • Energy Yield: It produces a net gain of 2 ATP molecules and 2 NADH molecules (an electron carrier).
  2. Krebs Cycle (or Citric Acid Cycle):
    • Location: This stage takes place in the matrix of the mitochondria.
    • Process: Before entering the cycle, each pyruvic acid molecule is converted into Acetyl-CoA. The Acetyl-CoA then enters the Krebs cycle, where it is completely oxidized. The carbon atoms are released as carbon dioxide (\(CO_2\)).
    • Energy Yield: For each glucose molecule (which yields two pyruvic acids), the Krebs cycle produces 2 ATP, 6 NADH, and 2 FADH\(_{2}\) molecules.
  3. Electron Transport Chain (ETC) and Oxidative Phosphorylation:
    • Location: This final stage occurs on the inner mitochondrial membrane.
    • Process: The high-energy electrons from NADH and FADH\(_{2}\) (produced in the previous stages) are passed along a series of protein complexes in the membrane. As electrons move, they release energy, which is used to pump protons (H\(^+\)) across the membrane, creating a proton gradient. Oxygen acts as the final electron acceptor, combining with electrons and protons to form water (\(H_2O\)).
    • Energy Yield: The flow of protons back across the membrane through an enzyme called ATP synthase drives the synthesis of a large amount of ATP (a process called oxidative phosphorylation). This stage produces the majority of the ATP, approximately 32-34 molecules.

(OR)

i) Parasitic Adaptations in Leech

The leech (a sanguivore, or blood-sucker) has several specific adaptations for its parasitic mode of life:

  1. Suckers: It possesses an anterior and a posterior sucker, which are used for strong adhesion to the host's body and for locomotion.
  2. Painless Bite: The leech's saliva contains an anaesthetic substance, which makes its bite painless, preventing the host from detecting its presence.
  3. Anticoagulant (Hirudin): Its saliva contains a powerful anticoagulant called hirudin, which prevents the host's blood from clotting, ensuring a continuous flow of blood.
  4. Jaws and Pharynx: It has three tiny, sharp jaws within its mouth that make a 'Y'-shaped, painless incision. The muscular pharynx creates a strong suction force to draw blood from the wound.
  5. Large Crop: The digestive tract has a large, expandable crop with many chambers (diverticula) that allows the leech to store a large volume of blood (several times its body weight). This enables it to survive for many months between meals.

ii) Define 'Reflex Arc'

A reflex arc is the complete neural pathway that a nerve impulse follows to produce a reflex action. It is an involuntary and rapid response to a stimulus that occurs without conscious thought.

The components of a typical reflex arc are:

  1. Receptor: A sense organ or cell that detects the stimulus (e.g., pain receptors in the skin).
  2. Sensory (or Afferent) Neuron: Transmits the nerve impulse from the receptor to the central nervous system (spinal cord).
  3. Integration Center (Interneuron): Located within the CNS (usually the spinal cord), it processes the signal and connects the sensory neuron to the motor neuron.
  4. Motor (or Efferent) Neuron: Carries the nerve impulse from the integration center to the effector.
  5. Effector: The muscle or gland that responds to the motor command (e.g., a muscle contracting to pull a hand away from a hot object).
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