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▌Multiple-Choice Questions (MCQs) Biology Unit 3 Energy Transformation

#Target Grade #12

1. Which of the following best defines metabolism?
a) The breakdown of complex molecules
b) The sum of all chemical reactions within a cell
c) The synthesis of biomolecules
d) The process of releasing energy

2. How does anabolism differ from catabolism?
a) Anabolism releases energy, while catabolism consumes energy.
b) Anabolism is a constructive process, while catabolism is a destructive process.
c) Anabolism occurs in mitochondria, while catabolism occurs in chloroplasts.
d) Anabolism breaks down glucose, while catabolism builds proteins.

3. In what part of a plant does photosynthesis primarily occur?
a) Root
b) Stem
c) Leaf
d) Flower

4. What is the primary function of stomata in leaves?
a) Absorbing sunlight
b) Regulating gas exchange and controlling water loss
c) Synthesizing chlorophyll
d) Storing carbohydrates

5. Which layer of a leaf contains the highest concentration of chloroplasts?
a) Spongy mesophyll
b) Palisade mesophyll
c) Epidermis
d) Cuticle

6. In which of the following organisms is chlorophyll "a" found?
a) All plants, algae, and cyanobacteria
b) Only green algae
c) Rhodophyta
d) Fungi

7. What is the function of carotenoids in photosynthesis?
a) They serve as primary light absorbers.
b) They act as accessory pigments that transfer energy to chlorophyll.
c) They function as waterproofing agents in leaves.
d) They act as enzymes for glucose synthesis.

8. Where do light-dependent reactions occur?
a) Stroma
b) Thylakoid membrane
c) Mitochondria
d) Cytoplasm

9. Where does the Calvin cycle (light-independent reactions) occur?
a) Thylakoid lumen
b) Stroma
c) Grana
d) Epidermis

10. Which of the following is produced during the light-dependent reactions?
a) CO₂
b) ATP and NADPH
c) Glucose
d) O₂ only

▌Answers and Explanations

1. Answer: b) The sum of all chemical reactions within a cell
Explanation: Metabolism encompasses both catabolic (breakdown) and anabolic (synthesis) reactions.

2. Answer: b) Anabolism is a constructive process, while catabolism is a destructive process.
Explanation: Anabolism builds complex molecules (e.g., proteins), whereas catabolism breaks them down.

3. Answer: c) Leaf
Explanation: Leaves contain mesophyll cells, which are rich in chloroplasts, the site of photosynthesis.

4. Answer: b) Regulating gas exchange and controlling water loss
Explanation: Stomata, controlled by guard cells, regulate CO₂ intake and the release of O₂ and H₂O.

5. Answer: b) Palisade mesophyll
Explanation: Palisade cells are densely packed with chloroplasts to maximize light absorption.

6. Answer: a) All plants, algae, and cyanobacteria
Explanation: Chlorophyll "a" is the primary photosynthetic pigment in most photosynthetic organisms.

7. Answer: b) They act as accessory pigments that transfer energy to chlorophyll.
Explanation: Carotenoids absorb wavelengths of light that chlorophyll cannot and transfer the energy.

8. Answer: b) Thylakoid membrane
Explanation: Light-dependent reactions utilize the thylakoid membranes to capture light energy.

9. Answer: b) Stroma
Explanation: The stroma contains the enzymes necessary for glucose synthesis during the Calvin cycle.

10. Answer: b) ATP and NADPH
Explanation: ATP and NADPH produced during the light-dependent reactions provide the energy and reducing power to drive the Calvin cycle; O₂ is a byproduct.

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Chemistry Grade 11 Unit 2 MCQ with explanation
#Target Grade #11 #12

1. Which compound contains a coordinate covalent bond?
A. O₂
B. NH₄⁺
C. CO₂
D. NaCl

2. Which molecule is polar?
A. CCl₄
B. CO₂
C. NH₃
D. CH₄

3. Which compound has both ionic and covalent bonds?
A. MgO
B. CH₃OH
C. KNO₃
D. Cl₂

4. Which molecule has a linear geometry?
A. H₂O
B. CO₂
C. NH₃
D. CH₄

5. What is the bond order in O₂⁺?
A. 2.5
B. 3.0
C. 1.5
D. 2.0

Answers and Explanations:

1. Answer: B. NH₄⁺
Explanation: NH₄⁺ has a coordinate covalent bond. This bond occurs when one atom provides both electrons for the shared pair, in this case, from NH₃ to H⁺.

2. Answer: C. NH₃

3. Answer: C. KNO₃
Explanation: KNO₃ contains ionic bonds between the K⁺ cation and the NO₃⁻ anion. Within the NO₃⁻ anion, covalent bonds exist between the nitrogen and oxygen atoms.

4. Answer: B. CO₂
Explanation: CO₂ is linear due to sp hybridization of the central carbon atom. Each carbon atom is double bonded to the Oxygen atoms.

5. Answer: A. 2.5

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#Chemistry Grade 11 Unit 2 MCQ with answers and Explanation
#Target grade: Grade 11 and 12


1. Which type of chemical bond involves a "sea of delocalized electrons"?
A. Ionic
B. Covalent
C. Metallic
D. Hydrogen

2. Which pair of elements is most likely to form a covalent compound?
A. Sodium and Chlorine
B. Carbon and Oxygen
C. Magnesium and Oxygen
D. Potassium and Fluorine

3. How many lone pairs of electrons are present in the Lewis structure of water (H₂O)?
A. 1
B. 2
C. 3
D. 4

4. Which molecule violates the octet rule?
A. CH₄
B. BF₃
C. NH₃
D. CO₂

5. Which of the following is a property of ionic compounds?
A. Low melting point
B. Conducts electricity in solid state
C. Soluble in organic solvents
D. Forms crystals

6. Which bond is the most polar?
A. H-Cl
B. H-O
C. H-F
D. H-N

7. Which compound contains a coordinate covalent bond?
A. O₂
B. NH₄⁺
C. CO₂
D. NaCl

8. How many resonance structures does the nitrate ion (NO₃⁻) have?
A. 1
B. 2
C. 3
D. 4

Answers and Explanations:

1. Answer: C. Metallic bonds are characterized by delocalized electrons in metals.

2. Answer: B. Nonmetals (C and O) share electrons covalently.

3. Answer: B. Oxygen has two lone pairs in H₂O.

4. Answer: B. BF₃ has only six electrons around boron.

5. Answer: D. Ionic compounds form crystalline solids.

6. Answer: C. H-F has the greatest electronegativity difference.

7. Answer: B. NH₄⁺ has a coordinate bond from H⁺ to NH₃.

8. Answer: C. NO₃⁻ exhibits three resonance structures.


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Math's Grade 12 Unit 3
#5 Mcq with answer

1. Which statement about random sampling is FALSE?
A) It minimizes investigator bias.
B) It ensures proportional representation of subgroups.
C) It requires careful planning.
D) It applies to any population type.

2. If a new value equal to the mean is added to a dataset, which statement is true?
A) Mean increases, standard deviation decreases.
B) Mean stays the same, standard deviation decreases.
C) Mean stays the same, standard deviation increases.
D) Mean and standard deviation remain unchanged.

3. In a distribution where Mean = 12, Median = 14, Mode = 16, the skewness is:
A) Positively skewed
B) Symmetrical
C) Negatively skewed 
D) Not determinable

4. If all values in a dataset are multiplied by 3, the variance becomes:
A) 3 times the original
B) 9 times the original
C) Unchanged
D) √3 times the original

5. Which sampling method divides the population into homogeneous subgroups?
A) Simple random sampling
B) Cluster sampling
C) Stratified sampling
D) Systematic sampling

Answer
1. B
2. B
3. C
4. B
5. C

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