Thiruvarur and Cuddalore
FIRST MID TERM TEST - 2024
Standard X - SCIENCE | Solved Question Paper
Question Paper
- The unit of 'g' is ms-2, it can be also expressed as __________.
a) cms⁻¹ b) N kg⁻¹ c) Nm² Kg⁻¹ d) cm² s⁻² - Power of lens is -4D, then its focal length is __________.
a) 4 m b) -40 m c) -0.25 m d) -2.5 m - 1 mole of any substance contains __________ molecules.
a) 6.023 x 10²³ b) 6.023 x 10⁻²³ c) 3.0115 x 10²³ d) 12.046 x 10²³ - Neon shows zero electron affinity due to __________.
a) stable arrangement of neutrons b) stable configurations of electrons c) reduced size d) Increased density - Oxygen is produced at what point during photosynthesis?
a) when ATP is connected to ADP b) when CO₂ is fixed c) when H₂O is splitted d) all of these - In Leech, locomotion is performed by __________.
a) Anterior sucker b) Parapodia c) Setae d) Contraction and Relaxation of muscles - Atrioventricular bundle was discovered by __________.
a) William Harvey b) His c) Edward Jenner d) None of the above - The wall of human heart is made of __________.
a) endocardium b) epicardium c) myocardium d) all the above - 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 - The eye defect "Presbyopia" can be corrected by __________.
a) convex lens b) concave lens c) convex mirror d) bifocal lenses
- Define Inertia. Give its classification.
- State Snell's Law.
- Differentiate Convex lens and Concave lens.
- Give any two examples for hetero diatomic molecules.
- Why should the light-dependent reaction occur before the light-independent reaction?
- State whether the statements are True or False. (Correct the false statement)
- i) Anaerobic respiration produces more ATP than Aerobic respiration.
- ii) Plant lose water by the process of transpiration.
- Fill in the blanks.
- i) Water enters into the root hair cell through __________ membrane.
- ii) __________ is the longest cell in our body.
- Calculate the velocity of a moving body of mass 5 kg whose linear momentum is 2.5 kg ms⁻¹.
- List out any five properties of light.
- A is a silvery white metal. A combines with O₂ to form B at 800°C.
a) The alloy of A is used in making the aircraft. Find A and B.
b) What is Rust? -
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 heart? -
i) Draw the structure of a neuron and label the parts. (2 marks)
ii) Write the reaction of photosynthesis. (2 marks) - Enumerate the functions of blood.
- Differentiate between Aerobic and Anaerobic respiration.
- Calculate the number of moles in:
i) 27 g of Al
ii) 1.51 x 10²³ molecules of NH₄Cl
- Deduce the equation of a 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. - 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'. (2 marks)
Solutions
Inertia: It is the inherent property of a body to resist any change in its state of rest or state of uniform motion, unless it is influenced by an external unbalanced force.
Classification:- Inertia of rest: The resistance of a body to change its state of rest. (e.g., a passenger falling backward when a bus starts suddenly).
- Inertia of motion: The resistance of a body to change its state of uniform motion. (e.g., a passenger falling forward when a moving bus stops suddenly).
- Inertia of direction: The resistance of a body to change its direction of motion. (e.g., being pushed sideways when a car takes a sharp turn).
Snell's Law states that for a given pair of media, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is a constant. This constant is called the refractive index of the second medium with respect to the first medium (\(\mu\)).
Formula: \[ \frac{\sin i}{\sin r} = \frac{\mu_2}{\mu_1} = \text{constant} \]| Feature | Convex Lens | Concave Lens |
|---|---|---|
| Shape | Thicker at the center and thinner at the edges. | Thinner at the center and thicker at the edges. |
| Action on Light | Converges a parallel beam of light. It is a converging lens. | Diverges a parallel beam of light. It is a diverging lens. |
| Focal Length | Positive focal length. | Negative focal length. |
| Image Formed | Forms real, inverted images (mostly) and a virtual, erect image. | Always forms a virtual, erect, and diminished image. |
Hetero diatomic molecules are molecules composed of two atoms of different elements. Two examples are:
- Hydrogen Chloride (HCl)
- Carbon Monoxide (CO)
The light-dependent reaction must occur first because it captures light energy and converts it into chemical energy in the form of ATP (Adenosine Triphosphate) and NADPH (Nicotinamide Adenine Dinucleotide Phosphate). These energy-rich molecules are essential to power the light-independent reactions (Calvin Cycle), where carbon dioxide is fixed into glucose. Without the ATP and NADPH produced in the light-dependent stage, the light-independent stage cannot proceed.
- i) Anaerobic respiration produces more ATP than Aerobic respiration.
Answer: False.
Correction: Aerobic respiration produces significantly more ATP (approximately 36-38 ATP per glucose molecule) than anaerobic respiration (only 2 ATP per glucose molecule). - ii) Plants lose water by the process of transpiration.
Answer: True.
- i) Water enters into the root hair cell through a semi-permeable membrane by the process of osmosis.
- ii) Neuron (or nerve cell) is the longest cell in our body.
Given:
Mass (m) = 5 kg
Linear Momentum (p) = 2.5 kg ms⁻¹
Formula:
Linear Momentum (p) = mass (m) × velocity (v)
Calculation:
\( v = \frac{p}{m} \)
\( v = \frac{2.5 \text{ kg ms⁻¹}}{5 \text{ kg}} \)
\( v = 0.5 \text{ ms⁻¹} \)
The velocity of the body is 0.5 m/s.
Five properties of light are:
- Rectilinear Propagation: Light travels in a straight line in a homogenous medium.
- Reflection: Light bounces back when it strikes a polished surface.
- Refraction: Light bends when it passes from one medium to another.
- Dispersion: White light splits into its constituent colors (VIBGYOR) when it passes through a prism.
- Speed: Light travels at a very high speed, approximately \( 3 \times 10^8 \) m/s in a vacuum.
a) The alloy of A is used in making the aircraft. Find A and B.
b) What is Rust?
a) The clue "alloy used in making aircraft" points to Duralumin, which is an alloy of Aluminium. Therefore, the silvery white metal 'A' is Aluminium.
- A = Aluminium (Al)
Aluminium combines with Oxygen (O₂) at high temperatures to form Aluminium Oxide (B).
Reaction: \( 4Al + 3O_2 \xrightarrow{800^\circ C} 2Al_2O_3 \)
- B = Aluminium Oxide (Al₂O₃)
b) What is Rust?
Rust is the common term for iron oxide, specifically hydrated iron(III) oxide. It is formed when iron or its alloys, like steel, corrode in the presence of oxygen and water. Its chemical formula is typically written as \( Fe_2O_3 \cdot nH_2O \).
a) Correct Matching:
- 1. Amphicribal → Fern (Vascular bundle type in rhizomes)
- 2. Cambium → Secondary growth (Responsible for increase in girth)
- 3. Amphivasal → Dracaena (Vascular bundle type)
- 4. Xylem → Conduction of water
b) Why is the Sinoatrial node called the pacemaker of heart?
The Sinoatrial (SA) node is called the pacemaker of the heart because it has the intrinsic ability to generate electrical impulses spontaneously and at a higher frequency (about 70-75 times per minute) than any other part of the heart's conduction system. These impulses spread throughout the atria and to the atrioventricular (AV) node, initiating the heartbeat and setting the normal sinus rhythm for the entire heart.
i) Structure of a Neuron:
(A diagram should be drawn here. The key parts to label are:)
- Cell Body (Soma/Cyton): Contains the nucleus and cytoplasm.
- Dendrites: Short, branched extensions that receive signals from other neurons.
- Axon: A long, slender projection that transmits electrical impulses away from the cell body.
- Myelin Sheath: An insulating layer that covers the axon and speeds up signal transmission.
- Nodes of Ranvier: Gaps in the myelin sheath.
- Axon Terminal: The end of the axon, where signals are passed to other cells.
ii) Reaction of Photosynthesis:
The overall balanced chemical equation for photosynthesis is:
\[ 6CO_2 + 12H_2O \xrightarrow{\text{Light Energy} + \text{Chlorophyll}} C_6H_{12}O_6 + 6O_2 + 6H_2O \]
(Carbon Dioxide + Water → Glucose + Oxygen + Water)
The main functions of blood are:
- Transport: It transports oxygen from the lungs to the tissues, and carbon dioxide from the tissues to the lungs. It also carries nutrients, hormones, enzymes, and waste products.
- Regulation: It helps in regulating body temperature, pH balance (acid-base balance), and water balance in the body.
- Protection: It plays a crucial role in the body's defense mechanism. White blood cells (leukocytes) fight against infections, and platelets help in blood clotting to prevent excessive blood loss from injuries.
| Feature | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen Requirement | Requires oxygen. | Does not require oxygen. |
| Location | Occurs in the cytoplasm and mitochondria. | Occurs only in the cytoplasm. |
| End Products | Carbon dioxide (CO₂), water (H₂O), and ATP. | Lactic acid (in animals) or Ethanol and CO₂ (in yeast), and ATP. |
| ATP Yield | High yield (approx. 36-38 ATP per glucose). | Low yield (only 2 ATP per glucose). |
| Breakdown of Glucose | Complete breakdown of glucose. | Incomplete breakdown of glucose. |
i) 27 g of Al
ii) 1.51 x 10²³ molecules of NH₄Cl
i) 27 g of Al
The atomic mass of Aluminium (Al) is 27 u. Therefore, the molar mass of Al is 27 g/mol.
Number of moles = \( \frac{\text{Given mass}}{\text{Molar mass}} \)
Number of moles = \( \frac{27 \text{ g}}{27 \text{ g/mol}} = 1 \text{ mole} \)
Answer: 1 mole
ii) 1.51 x 10²³ molecules of NH₄Cl
Avogadro's number (\(N_A\)) = \( 6.023 \times 10^{23} \) molecules/mol.
Number of moles = \( \frac{\text{Number of molecules}}{\text{Avogadro's number}} \)
Number of moles = \( \frac{1.51 \times 10^{23}}{6.023 \times 10^{23}} \)
Number of moles ≈ \( \frac{1}{4} = 0.25 \text{ moles} \)
Answer: 0.25 moles
Newton's Second Law of Motion: It states that the rate of change of momentum of an object is directly proportional to the applied unbalanced force and takes place in the direction of the force.
Derivation of F = ma:
- Consider an object of mass 'm' moving with an initial velocity 'u'.
- A force 'F' is applied on the object for a time 't', causing its velocity to change to 'v'.
- Initial momentum of the object, \( p_i = mu \).
- Final momentum of the object, \( p_f = mv \).
- Change in momentum, \( \Delta p = p_f - p_i = mv - mu = m(v - u) \).
- Rate of change of momentum = \( \frac{\text{Change in momentum}}{\text{Time}} = \frac{m(v - u)}{t} \).
- According to Newton's second law, \( F \propto \frac{m(v - u)}{t} \).
- We know that acceleration \( a = \frac{v - u}{t} \). Substituting this, we get \( F \propto ma \).
- To convert the proportionality into an equation, we introduce a constant of proportionality, 'k': \( F = kma \).
- The unit of force (1 Newton) is defined as the force required to produce an acceleration of 1 ms⁻² in an object of mass 1 kg. By substituting F=1 N, m=1 kg, and a=1 ms⁻², we get k=1.
- Therefore, the equation becomes: \( \mathbf{F = ma} \).
ii) Assertion and Reason - (2 marks)
i) Salient Features of Modern Atomic Theory:
- An atom is no longer considered indivisible. It is composed of subatomic particles: protons, neutrons, and electrons.
- Atoms of the same element may not be identical in all respects. They can have different atomic masses, as in the case of isotopes (e.g., ¹H, ²H, ³H).
- Atoms of different elements may have the same atomic mass, as in the case of isobars (e.g., ⁴⁰Ar, ⁴⁰K, ⁴⁰Ca).
- An atom is the smallest particle that takes part in a chemical reaction.
- The mass of an atom can be converted into energy according to Einstein's equation, \( E = mc^2 \).
- The energy of electrons in an atom is quantized, meaning they can only exist in specific energy levels or orbitals.
ii) Assertion and Reason:
Assertion (A): An uncleaned copper vessel is covered with a greenish layer.
Reason (R): Copper is not attacked by Alkali.
Analysis:
- Assertion (A) is True. Copper reacts with moist air containing carbon dioxide and oxygen to form a greenish layer of basic copper carbonate (\(CuCO_3 \cdot Cu(OH)_2\)).
- Reason (R) is True. Copper is a relatively unreactive metal and is resistant to attack by alkalis.
- However, the Reason (R) does not explain the Assertion (A). The formation of the greenish layer is due to reaction with components of air, not its non-reactivity with alkalis.
Aerobic respiration is the process of breaking down glucose in the presence of oxygen to produce a large amount of energy (ATP). It occurs in three main stages:
-
Glycolysis:
- Location: Cytoplasm.
- Process: This is the initial stage where one 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.
- Products: For each glucose molecule, the net gain is 2 ATP molecules and 2 NADH molecules.
-
Krebs Cycle (or Citric Acid Cycle):
- Location: Mitochondrial matrix.
- Process: Pyruvic acid from glycolysis enters the mitochondria and is first converted into Acetyl-CoA. This Acetyl-CoA then enters the Krebs cycle, a series of enzyme-catalyzed reactions that completely oxidize the carbon atoms.
- Products: For each glucose molecule (i.e., two turns of the cycle), it produces carbon dioxide (CO₂), 2 ATP, 6 NADH, and 2 FADH₂.
-
Electron Transport Chain (ETC) and Oxidative Phosphorylation:
- Location: Inner mitochondrial membrane.
- Process: The high-energy electrons from NADH and FADH₂ (produced in the previous stages) are passed along a series of protein complexes embedded in the inner mitochondrial membrane. As electrons move down the chain, energy is released and used to pump protons (H⁺) across the membrane, creating a proton gradient. The flow of protons back into the matrix through an enzyme called ATP synthase drives the synthesis of ATP. Oxygen acts as the final electron acceptor, combining with electrons and protons to form water.
- Products: This stage produces the majority of the ATP, about 32-34 molecules.
ii) Define 'Reflex arc'. (2 marks)
i) Parasitic Adaptations in Leech:
Leeches exhibit several adaptations for their ectoparasitic (blood-sucking) mode of life:
- Suckers: They possess a powerful anterior sucker for feeding and a posterior sucker for attachment and locomotion, allowing them to firmly grip the host.
- Jaws and Teeth: The mouth, located in the anterior sucker, is equipped with three jaws bearing minute teeth. These create a painless, Y-shaped incision on the host's skin.
- Anticoagulant Saliva: The salivary glands secrete hirudin, a potent anticoagulant that prevents the host's blood from clotting, ensuring a continuous flow of blood.
- Blood Storage: The crop, a part of the alimentary canal, is greatly enlarged with many diverticula (pouches). This allows the leech to store a large volume of blood, often several times its own body weight, which can sustain it for months.
- Muscular Pharynx: A muscular pharynx acts as a powerful pump to suck blood from the host's wound.
ii) Define 'Reflex arc':
A reflex arc is the complete neural pathway that a nerve impulse follows to mediate a reflex action. It is an involuntary and rapid response to a stimulus. The pathway typically includes:
- A sensory receptor to detect the stimulus.
- A sensory (afferent) neuron to transmit the signal to the central nervous system.
- An interneuron (or association neuron) within the spinal cord or brainstem that processes the signal.
- A motor (efferent) neuron to carry the command away from the central nervous system.
- An effector organ (a muscle or gland) that carries out the response.