Key Concept: Leaves as Food Factories

b) Because they contain chlorophyll and stomata for gas exchange and sunlight absorption
[Solution Description]
Leaves contain chlorophyll, which captures sunlight necessary for photosynthesis. They also have stomata, tiny pores that facilitate gas exchange (oxygen and carbon dioxide). These features make leaves the main sites for food production in plants.
From the syllabus: "Leaves are the primary sites for photosynthesis due to the presence of chlorophyll."

Key Concept: Transport in Plants

d) Phloem
[Solution Description]
Phloem is the vascular tissue in plants that transports food (glucose) synthesized in the leaves to all other parts. Xylem transports water and minerals, but phloem is specialized for food transport.
From the syllabus: "Phloem carries food (glucose) from leaves to all parts of the plant."

Key Concept: Photosynthesis, Respiration

c) Respiration rate decreases, starch content decreases
[Solution Description]
Photosynthesis requires carbon dioxide and sunlight to produce glucose, which is converted to starch. Without these, photosynthesis stops, reducing starch production. Respiration continues but at a lower rate due to limited glucose availability. Therefore, both the respiration rate and starch content will decrease.

Key Concept: Photosynthesis and Food Production in Plants

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that leaves are the primary site for photosynthesis in plants, which is correct as they contain chlorophyll and perform the process. The reason mentions stomata help in gas exchange, which is also true since stomata allow carbon dioxide to enter and oxygen to exit during photosynthesis. Additionally, the reason correctly explains why leaves are the primary site (due to gas exchange via stomata). Therefore, both statements are true, and the reason is a valid explanation.

Key Concept: Photosynthesis Requirement

b) It provides energy for chlorophyll to produce starch.
[Solution Description]
Sunlight provides the energy required for photosynthesis, the process by which plants convert carbon dioxide and water into glucose (which is then stored as starch). Chlorophyll captures sunlight, making it essential for this process. Without sunlight, photosynthesis cannot occur, and no starch is produced.

Key Concept: Chlorophyll, Leaf Structure

c) To increase surface area for sunlight absorption and contain chlorophyll.
[Solution Description]
Leaves are broad and flat to maximize surface area for sunlight absorption. The green pigment, chlorophyll, captures sunlight efficiently for photosynthesis, which produces starch. This adaptation ensures optimal food production.

Key Concept: Photosynthesis and Chlorophyll

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that plants produce their own food through photosynthesis instead of eating like animals, which is a key difference between plants and animals. The reason correctly explains that chlorophyll in leaves captures sunlight, which is necessary for photosynthesis to produce starch. Hence, both statements are true, and the reason correctly explains the assertion.

Key Concept: Essential gas for photosynthesis

c) Carbon dioxide
[Solution Description]
Plants require carbon dioxide ($CO_2$) from the air for photosynthesis. During this process, they combine carbon dioxide with water in the presence of sunlight and chlorophyll to produce glucose (food) and oxygen. Without carbon dioxide, photosynthesis cannot occur.

Key Concept: Sunlight, Water, Soil Nutrients

b) Stunted growth with yellow leaves
[Solution Description]
The plant lacking essential soil nutrients will show stunted growth because it cannot synthesize enough food despite having sunlight and water. It may develop yellow leaves (chlorosis) due to nutrient deficiency.

Key Concept: Effect of Water on Plants

c) May die due to lack of water
[Solution Description]
The syllabus states that a plant placed in sunlight without water may die due to lack of water, even though it gets sunlight.

Key Concept: Plant Growth, Photosynthesis, Respiration

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
From the activity, Pot C (kept in dark but watered) showed reduced growth compared to Pot A because photosynthesis requires sunlight to produce glucose ($Glucose + Oxygen \rightarrow Carbon\ dioxide + Water + Energy$). Without glucose, plants cannot generate energy via respiration, leading to eventual death despite initial growth from water absorption. Thus, both Assertion and Reason are true, and Reason correctly explains Assertion.

Key Concept: Sunlight, Water, Experimental Setup

b) Only Plant Y due to lack of water
[Solution Description]
Plant Y will show the least growth because lack of water prevents nutrient uptake and photosynthesis. Plant Z will grow poorly due to no sunlight, but Plant Y may die or show minimal growth due to dehydration.

Key Concept: Role of water and sunlight in plant growth

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The Assertion states that Pot A grows the most due to sunlight and water availability, which matches experimental observations. The Reason explains that these factors are required for photosynthesis to produce glucose, directly linking them to plant growth. Thus, both statements are true, and the Reason correctly explains the Assertion.

Key Concept: Comparative Growth Analysis

b) Pot C only
[Solution Description]
According to Activity 10.1, Pot A (sunlight + water) shows maximum growth. Pot C (dark + water) grows less than Pot A because sunlight is absent, limiting photosynthesis even though water is available. Pot B (sunlight, no water) may die due to water deficiency. Hence, Pot C exhibits stunted growth compared to Pot A.

Key Concept: Role of Water and Sunlight

b) Leaves will turn yellow and may wilt
[Solution Description]
The plant is kept in the dark but given water, similar to Pot C in Activity 10.1. Without sunlight, photosynthesis cannot occur properly. As a result, the leaves lose their green pigment (chlorophyll) due to the absence of light, leading to yellowing or wilting. Thus, the leaves will turn yellow over time.

Key Concept: Photosynthesis Importance

d) To provide energy for glucose production
[Solution Description]
Photosynthesis converts carbon dioxide and water into glucose and oxygen using sunlight energy. The equation is: $\text{carbon dioxide} + \text{water} + \text{sunlight} \rightarrow \text{glucose} + \text{oxygen}$. Here, sunlight is essential as it provides the energy needed to drive this chemical reaction, enabling food (glucose) production for the plant.

Key Concept: Growth measurement, Variable control

c) 66.67\%
[Solution Description]
To isolate sunlight's effect: Compare Pot A (sunlight+water) vs Pot C (water only). Growth due to sunlight = Growth of A - Growth of C. Absolute growth: A=15cm, C=5cm. Sunlight contribution=15-5=10cm. Total possible growth=15cm. Percentage=(10/15)×100≈66.67\%.

Key Concept: Observation on leaf color

b) Yellow
[Solution Description]
Since Pot C is kept in the dark, the plant cannot perform photosynthesis, leading to a lack of chlorophyll production. Without chlorophyll, leaves turn yellow due to the absence of green pigmentation, indicating poor health or stunted growth.

Key Concept: Role of sunlight vs. water in plant growth

c) Plants can survive longer without sunlight than without water
[Solution Description]
Although Pot B receives sunlight, the lack of water prevents nutrient absorption and transpiration, causing the plant to wilt and eventually die. Pot C, despite lacking sunlight, still has water for basic cellular functions, allowing some minimal survival before deterioration occurs.

Key Concept: Leaf production rate, Experimental conditions

c) Missing both factors has greater negative effect than their separate impacts
[Solution Description]
Missing both factors (Pot B) has worse effect than missing one factor (Pot C). Pot B (no water): 1 leaf shows severe stress. Pot C (no light): 3 leaves indicates moderate stress. The difference between 1 leaf (both factors missing) and average of single-factor effects (8+3)/2=5.5 shows synergistic negative impact.

Key Concept: Photosynthesis, Chlorophyll, Starch Production

d) Assertion is false, but Reason is true.
[Solution Description]
The assertion claims that a plant can produce starch without carbon dioxide if sunlight and chlorophyll are present. However, according to the syllabus, Activity 10.4 demonstrates that carbon dioxide is essential for starch production in plants. The part of the leaf exposed to air (containing $CO_2$) turns blue-black with iodine, indicating starch, while the part inside the bottle (no $CO_2$) shows no color change. Thus, the assertion is false. The reason states that carbon dioxide is not necessary for photosynthesis, which contradicts the syllabus evidence showing $CO_2$ is indeed required. Therefore, the reason is also false.

Key Concept: Photosynthesis and Chlorophyll

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
According to the syllabus, chlorophyll is a green pigment present in leaves that captures sunlight efficiently. This sunlight is used in the process of photosynthesis, where plants prepare food in the form of starch. Thus, both the Assertion and Reason are true, and the Reason correctly explains why chlorophyll is important for photosynthesis.

Key Concept: Starch Detection Test

b) Blue-black
[Solution Description]
In Activity 10.2, iodine solution turns blue-black in the presence of starch, as observed in the green parts of the leaf. This confirms that starch is produced in leaves through photosynthesis.

Key Concept: Photosynthesis, Chlorophyll, Starch Test

c) Starch is present only in the green parts of the leaf.
[Solution Description]
The variegated leaf has both green (containing chlorophyll) and white (lacking chlorophyll) patches. After boiling and treating with iodine, starch is detected only in the green parts because chlorophyll is essential for photosynthesis, which produces starch. The absence of color change in non-green areas indicates no starch production due to lack of chlorophyll.

Key Concept: Starch Storage, Leaf Structure

c) Starch is insoluble and does not disrupt cellular osmotic balance.
[Solution Description]
Starch is insoluble in water and compact, making it efficient for long-term storage without affecting osmotic balance. Glucose, being soluble, would draw water into cells via osmosis, causing structural issues.

Key Concept: Starch Test

d) The leaf contains stored starch
[Solution Description]
Iodine solution turns blue-black in the presence of starch. The observation confirms that the leaf contains starch, which is produced during photosynthesis and stored in the leaf. This validates that the leaf functions as a 'food factory' for the plant.

Key Concept: Photosynthesis, Chlorophyll

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]
The assertion states that non-green patches of a leaf will always test negative for starch under the iodine test. This is true because chlorophyll, which is absent in non-green patches, is necessary for photosynthesis and subsequent starch production.
The reason states that chlorophyll is essential for capturing sunlight and synthesizing starch through photosynthesis. This is also true, as chlorophyll absorbs sunlight and facilitates the conversion of carbon dioxide and water into glucose (which is stored as starch).
However, the reason does not explicitly explain why non-green patches lack starch; it only explains the role of chlorophyll in general. Thus, both statements are true, but the reason does not directly explain the assertion.
Therefore, the correct answer is: Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

Key Concept: Chlorophyll Function

c) Chlorophyll
[Solution Description] Chlorophyll is the green pigment present in leaves that captures sunlight for photosynthesis. It is essential for the production of starch in plants.

Key Concept: Role of Chlorophyll

c) Green patches
[Solution Description]
From Table 10.2, only the green patches of the leaf turn blue-black, showing the presence of starch, due to chlorophyll.

Key Concept: Role of Chlorophyll, Experimental Observations

b) Only the green patches turn blue-black
[Solution Description]
The green patches contain chlorophyll, which is essential for photosynthesis to produce starch. In sunlight, chlorophyll enables starch production, turning blue-black when exposed to iodine. Non-green patches lack sufficient chlorophyll to produce detectable starch, so they do not change color.
Step-by-step reasoning:
1. Green patches have chlorophyll → photosynthesis occurs → starch produced → blue-black color with iodine.
2. Non-green patches lack enough chlorophyll → no significant starch production → no color change with iodine.
Thus, the correct observation is: green patches turn blue-black; non-green patches remain unchanged.

Key Concept: Role of Sunlight in Photosynthesis

c) Sunlight is essential for chlorophyll to drive the process
[Solution Description]
Sunlight provides the energy required for photosynthesis. Without light, chlorophyll cannot convert CO$_2$ and water into starch. Thus, even if other conditions are met, no starch is formed without sunlight.

Key Concept: Experimental Observations, Photosynthesis and Chlorophyll

c) Starch is converted to sugars in the dark
[Solution Description]
Starch production requires sunlight. Steps:
1. No sunlight → no photosynthesis → no starch synthesis.
2. Existing starch is used up or converted to sugars for energy during darkness.
3. Iodine test shows no starch (no blue-black).
Even if chlorophyll is present, darkness prevents starch formation.

Key Concept: Photosynthesis Inputs

b) Carbon dioxide
[Solution Description]
The process of photosynthesis requires sunlight, water, carbon dioxide, and chlorophyll to produce starch. These are the essential components for starch production.

Key Concept: Starch Detection

c) Perform the iodine test
[Solution Description]
The iodine test is used to detect starch in leaves. When iodine solution is added to a decolorized leaf, the appearance of a blue-black color confirms the presence of starch.

Key Concept: Chlorophyll Role

c) White petals of a flower[Solution Description]Starch is primarily synthesized in the green parts of the plant where chlorophyll is present (like leaves). Non-green parts such as roots or stems without chlorophyll do not produce starch unless it is transported there from the leaves. For example, potato tubers (modified stems) store starch but do not produce it themselves.

Key Concept: Photosynthesis, Carbon Dioxide Requirement, Starch Storage

c) Only the part outside the bottle turns blue-black, as it had access to CO$_2$
[Solution Description]
Caustic soda absorbs carbon dioxide from the air inside the bottle. Therefore, the part of the leaf inside the bottle does not receive any carbon dioxide, an essential requirement for photosynthesis. The part outside the bottle receives sufficient carbon dioxide and can perform photosynthesis, producing starch. When tested with iodine, only the outer part (exposed to CO$_2$) will turn blue-black, while the inner part (deprived of CO$_2$) will show no change.
Step-by-Step Explanation:
1. The enclosed part has no CO$_2$ due to caustic soda absorption, halting photosynthesis.
2. The exposed part uses available CO$_2$, water, and sunlight to produce glucose and store it as starch.
3. Iodine reacts with starch in the exposed part, turning it blue-black.
4. The enclosed part lacks starch, so no color change occurs.

Key Concept: Role of Carbon Dioxide in Photosynthesis

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that the part of the leaf inside the bottle does not show starch formation due to the absence of carbon dioxide. This is correct because caustic soda removes carbon dioxide from the air inside the bottle, preventing photosynthesis. The reason explains this by stating that caustic soda absorbs carbon dioxide, which is necessary for starch production during photosynthesis. Both statements are true, and the reason correctly explains the assertion.

Key Concept: Role of Carbon Dioxide in Photosynthesis

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
- **Assertion:** According to Activity 10.4, the leaf part inside the bottle (with no carbon dioxide due to caustic soda) does not form starch and thus does not turn blue-black. This is true.
- **Reason:** The reason correctly states that caustic soda absorbs carbon dioxide, a necessary component for photosynthesis (starch formation). This is also true.
- **Connection:** The absence of carbon dioxide directly prevents starch formation, so the Reason explains the Assertion correctly.

Key Concept: Chlorophyll Function

c) It captures sunlight energy for photosynthesis
[Solution Description]
Chlorophyll is a green pigment found in chloroplasts that captures sunlight energy. This energy is used to convert carbon dioxide and water into glucose and oxygen during photosynthesis. Without chlorophyll, the plant cannot harness sunlight energy, making it essential for the process.

Key Concept: Carbon Dioxide in Photosynthesis

c) Carbon dioxide
[Solution Description]
The experiment with caustic soda confirms that carbon dioxide is necessary for starch synthesis. When a leaf is kept in an environment without carbon dioxide, it fails to produce starch, as tested by iodine solution.

Key Concept: Gas exchange, Photosynthesis products

d) They open to absorb carbon dioxide and release oxygen
[Solution Description]
Stomata open during daylight to facilitate gas exchange for photosynthesis:
1) Open stomata allow CO$_2$ to enter - the raw material for photosynthesis.
2) Oxygen produced during photosynthesis exits through these pores.
3) This exchange maintains the concentration gradient needed for continuous CO$_2$ uptake.
4) Without open stomata, CO$_2$ cannot enter, halting food production.
The process is vital because it enables the plant to obtain the necessary carbon dioxide while releasing oxygen, maintaining both photosynthesis and atmospheric balance.

Key Concept: Role of carbon dioxide in photosynthesis

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that carbon dioxide is essential for photosynthesis, which is correct as per the syllabus (10.2.2 and 10.2.3). The reason refers to the experimental observation where leaves don't produce starch without CO$_2$ (Activity 10.4), which correctly explains why CO$_2$ is essential. Both statements are true and the reason properly explains the assertion.

Key Concept: Photosynthesis equation, Energy conversion

c) Uses 60 carbon dioxide molecules and transforms light to chemical energy
[Solution Description]
Based on the photosynthesis equation:
$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$
For 10 glucose molecules:
- Requires 60 CO$_2$ molecules and 60 H$_2$O molecules
- Produces 60 O$_2$ molecules
Energy transformation:
1) Light energy is absorbed by chlorophyll
2) Converted to chemical energy stored in glucose bonds
3) This energy will later be released during respiration
The process shows how solar energy becomes biologically useful energy stored in food molecules.

Key Concept: Photosynthesis Equation

c) Carbon dioxide + Water → Glucose + Oxygen
[Solution Description]
The correct word equation for photosynthesis is: Carbon dioxide + Water → Glucose + Oxygen, in the presence of sunlight and chlorophyll. This process converts light energy into chemical energy stored as glucose.

Key Concept: Leaf Function

c) Leaves
[Solution Description]
Leaves contain chlorophyll and are the main site for photosynthesis. Other green parts can also perform photosynthesis, but leaves are the primary "food factories."

Key Concept: Photosynthesis, Oxygen Release, Chlorophyll

c) Chlorophyll absorbs blue light poorly, leading to insufficient glucose production
[Solution Description]
Chlorophyll primarily absorbs red and blue light for photosynthesis but reflects green light. When only blue light is available, some photosynthesis occurs, but it may not be sufficient to sustain the plant's needs. Additionally, other wavelengths (like red) are crucial for optimal photosynthetic efficiency. The wilting suggests inadequate glucose production due to inefficient photosynthesis under monochromatic blue light.

Key Concept: Photosynthesis Raw Materials

c) Oxygen
[Solution Description]
Photosynthesis requires carbon dioxide, water, sunlight, and chlorophyll. Oxygen is released as a byproduct, not used as a raw material.

Key Concept: Stomata, Gas Exchange, Photosynthesis Conditions

d) Photosynthesis declines sharply due to restricted carbon dioxide uptake
[Solution Description]
Stomata are predominantly located on the lower surface of leaves. Coating this surface with petroleum jelly blocks stomata, preventing gas exchange (CO$_2$ intake and O$_2$ release). Since CO$_2$ cannot enter, photosynthesis slows down significantly despite sunlight and water availability. The upper surface has fewer stomata, so minimal photosynthesis occurs.

Key Concept: Role of Carbon Dioxide

c) Only the uncovered part will produce starch
[Solution Description]
Caustic soda absorbs carbon dioxide, depriving the covered part of the leaf of this essential input for photosynthesis. Only the uncovered part (exposed to air with carbon dioxide) will produce starch. The covered part will show no starch production.

Key Concept: Chlorophyll role, Gas exchange

c) Neither absorbs CO$_2$ nor releases oxygen
[Solution Description]
Non-green regions lack chlorophyll, so they cannot perform photosynthesis. Therefore, they neither take in carbon dioxide nor release oxygen. Gas exchange only happens in green regions where chlorophyll is present.

Key Concept: Photosynthesis, Chlorophyll, Carbon Dioxide

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion describes the experimental observation where the part of the leaf exposed to carbon dioxide turns blue-black with iodine, indicating starch presence. This is because carbon dioxide is essential for photosynthesis, leading to starch synthesis. The reason explains why the enclosed part did not turn blue-black: caustic soda absorbs carbon dioxide, preventing photosynthesis. Since both the assertion and reason are true, and the reason correctly explains the assertion, the correct answer is a).

Key Concept: Photosynthesis equation, Energy conversion

b) 200 units stored in glucose
[Solution Description]
Total energy input = 1000 units. Subtracting losses: Heat (300) + Water absorption (500) = 800 units lost. Net available energy = 1000 - 800 = 200 units. This represents the energy theoretically converted into chemical energy (glucose) during photosynthesis.

Key Concept: Photosynthesis, Oxygen Release, Starch Storage

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that depriving a plant of carbon dioxide in sunlight prevents starch formation. This is true because carbon dioxide is required for photosynthesis, and without it, the process cannot produce glucose (which converts to starch). The reason correctly explains this by stating carbon dioxide's role as a reactant in photosynthesis, leading to glucose production and subsequent starch storage. Both statements are true, and the reason directly explains the assertion.

Key Concept: Photosynthesis, Respiration, Starch Storage

c) Stored as starch and later reconverted to glucose for respiration
[Solution Description]
During photosynthesis, glucose is produced and immediately used for energy or stored as starch. At night, when photosynthesis stops due to lack of sunlight, the plant breaks down stored starch back into glucose for respiration. The glucose produced during the day is either consumed for energy or converted into starch for storage.
Step-by-Step Explanation:
1. Photosynthesis occurs during the day, producing glucose and oxygen.
2. Some glucose is used for immediate energy needs via respiration.
3. Excess glucose is converted into starch for storage (e.g., in potatoes).
4. At night, starch is broken down into glucose for respiration.
5. Therefore, glucose is not retained in its original form but stored as starch or respired.

Key Concept: Chlorophyll Role

b) It absorbs sunlight necessary for photosynthesis
[Solution Description]
Chlorophyll is a green pigment found in leaves that absorbs sunlight. This absorbed light energy is essential for converting carbon dioxide and water into glucose and oxygen during photosynthesis. Without chlorophyll, this process cannot occur.

Key Concept: Leaf Structure

b) They increase surface area for sunlight absorption
[Solution Description]
Broad and flat leaves have a larger surface area which allows them to absorb more sunlight. More sunlight means more energy available for photosynthesis. Additionally, their structure facilitates efficient gas exchange with the environment, enhancing the absorption of carbon dioxide and release of oxygen.

Key Concept: Photosynthesis Byproduct

c) Oxygen
[Solution Description]
From the word equation, oxygen ($O_2$) is released as a byproduct during photosynthesis.

Key Concept: Photosynthesis Conditions, Limiting Factors

b) Photosynthesis will stop, but respiration will continue until stored glucose is exhausted
[Solution Description]
Photosynthesis requires carbon dioxide as a reactant. Without it, photosynthesis cannot occur, so no glucose or oxygen will be produced. Respiration, however, can continue until the stored glucose is depleted. Initially, the plant will respire using stored glucose, releasing carbon dioxide and water. However, without photosynthesis replenishing glucose, respiration will eventually stop.

Key Concept: Outcome of Photosynthesis

c) Glucose and Oxygen
[Solution Description]
The primary products of photosynthesis are glucose (used for energy and storage) and oxygen (released into the atmosphere as a byproduct).

Key Concept: Photosynthesis Components

c) Oxygen
[Solution Description]
The essential components for photosynthesis are carbon dioxide, water, sunlight, and chlorophyll. Oxygen is a byproduct, not a requirement.

Key Concept: Gas Exchange in Photosynthesis

d) Stomata
[Solution Description]
The tiny pores on the surface of leaves called stomata are responsible for gas exchange during photosynthesis. They allow carbon dioxide to enter and oxygen to exit the leaf.

Key Concept: Photosynthesis Equation

c) Oxygen
[Solution Description]
During photosynthesis, carbon dioxide and water are converted into glucose and oxygen in the presence of sunlight and chlorophyll. Oxygen is released as a by-product.

Key Concept: Role of Sunlight in Photosynthesis

c) Decreases gradually
[Solution Description]
Photosynthesis requires sunlight. Without sunlight, the process slows down, reducing the exchange of gases (carbon dioxide intake and oxygen release) in the leaves.

Key Concept: Destarching, Iodine Test

d) The leaf part cannot make starch without carbon dioxide.
[Solution Description]
Caustic soda absorbs carbon dioxide from the air inside the bottle. Without carbon dioxide, the part of the leaf inside the bottle cannot perform photosynthesis and thus cannot produce starch. Since iodine turns blue-black in the presence of starch, the leaf section inside the bottle will show no color change.

Key Concept: Stomata in Leaves

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that stomata are tiny pores present on the lower surface of leaves, which is true as observed in Activity 10.6. The reason states that stomata help in the exchange of gases like oxygen and carbon dioxide during photosynthesis, which is also true. Furthermore, the reason correctly explains why stomata are present on leaves, as they facilitate gas exchange necessary for photosynthesis.

Key Concept: Stomata Function

c) To facilitate gas exchange
[Solution Description]
Stomata are tiny pores found on the surface of leaves. Their main function is to facilitate gas exchange during photosynthesis. They allow carbon dioxide (\$CO_2\$) to enter the leaf and oxygen (\$O_2\$) to exit, which is essential for photosynthesis.

Key Concept: Photosynthesis equation, Gas exchange

b) Photosynthesis rate decreases due to photorespiration
[Solution Description]
High oxygen concentrations can lead to photorespiration, a process that competes with photosynthesis. This occurs because oxygen binds to the enzyme Rubisco instead of carbon dioxide, reducing the efficiency of photosynthesis. The correct answer is the option indicating a decrease in photosynthesis rate.

Key Concept: Photosynthesis Equation

c) Carbon dioxide
[Solution Description]
The photosynthesis equation is: \$ \text{Carbon dioxide} + \text{Water} \xrightarrow{\text{Sunlight, Chlorophyll}} \text{Glucose} + \text{Oxygen} \$. From this equation, it is clear that carbon dioxide (\$CO_2\$) is the gas required by plants for photosynthesis.

Key Concept: Xylem Transport, Phloem Transport

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that xylem transport is unidirectional (upward) due to transpiration pull, which is true as transpiration creates a negative pressure that draws water upward from roots. The reason correctly explains that xylem cells are dead and depend on passive mechanisms like transpiration pull for transport. On the other hand, the phloem involves active transport (bidirectional) via living sieve tubes that adjust to the plant's requirements. Both statements are factually accurate, and the reason provides the correct explanation for the assertion.

Key Concept: Transport of water and minerals

c) Xylem
[Solution Description]
The xylem is the thin tube-like structure present in the stem, branches, and leaves of plants that transports water and dissolved minerals from the roots to other parts of the plant.

Key Concept: Xylem-phloem interaction, Transpiration

c) Transpiration exceeds water absorption, creating a temporary water deficit.
[Solution Description]
High temperature and wind increase transpiration rate, causing rapid water loss through stomata. Though xylem transports water, excessive transpiration outpaces water absorption by roots, leading to temporary wilting. Phloem’s role in sugar transport is unaffected but irrelevant here.

Key Concept: Food Transport

c) Phloem
[Solution Description]
The food prepared in the leaves during photosynthesis is transported through the phloem. The phloem is a specialized tissue that carries nutrients like sugars to all parts of the plant, including storage organs like seeds and roots.

Key Concept: Water Movement Experiment

c) In the stem, leaves, and flowers
[Solution Description]
When the stem of a plant is placed in red-coloured water, the xylem transports the coloured water upwards. The observation showed red coloration in the stem, leaves, and flowers, indicating the path of water and mineral transport through the xylem.

Key Concept: Importance of water and minerals for plant growth

b) Involved in the process of photosynthesis[Solution Description]Water is essential for photosynthesis, where plants use sunlight to synthesize nutrients from carbon dioxide and water. It also helps in nutrient transport and maintaining cell turgidity.

Key Concept: Xylem function, Water transport mechanism

c) The plant utilized all minerals in root metabolic processes before they could reach the leaves.
[Solution Description]
The xylem transports both water and dissolved minerals from roots to other plant parts. However, if the leaves show the dye but not the minerals, it indicates selective transport or mineral utilization elsewhere. Since the dye moves with water via the xylem, the minerals might have been used up by the plant before reaching the leaves or were not absorbed properly due to root selectivity.

Key Concept: Mineral Transport

c) Through xylem along with water
[Solution Description]
Minerals are absorbed by the roots along with water. They are transported upwards through the xylem vessels, which act as a continuous pipeline from roots to leaves, ensuring nutrient distribution.

Key Concept: Xylem Transport

c) Transports water and minerals upwards from roots
[Solution Description]
Xylem is responsible for transporting water and dissolved minerals from the roots to other parts of the plant, which supports photosynthesis and overall growth.

Key Concept: Mineral Absorption

c) Act as important nutrients for growth
[Solution Description]
Minerals are essential nutrients required for various physiological functions in plants, including enzyme activity, structural support, and synthesis of important molecules like chlorophyll.

Key Concept: Xylem transport, Root absorption

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.
[Solution Description]

Key Concept: Mineral transport, Selective absorption

b) Potassium transporters preferentially bind sodium
[Solution Description]
Excess Na$^+$ competes with K$^+$ for transport proteins during selective mineral absorption. Although K$^+$ is equally available, sodium ions interfere with its uptake, leading to potassium deficiency that restricts metabolic processes like enzyme activation and stomatal regulation.

Key Concept: Transport Mechanism

c) Xylem[Solution Description]Water and minerals are primarily transported through the xylem, as it is specialized for upward movement of these substances from the roots to other parts of the plant.

Key Concept: Transpiration pull, Xylem cohesion-tension theory

d) Water transport stops above the obstruction
[Solution Description]
The cohesion-tension theory states that water is pulled upward as a continuous column due to transpiration from leaves. An obstruction breaks this column, preventing water transport above the blockage even if roots continue absorbing water.

Key Concept: Food Storage

d) Roots
[Solution Description]
Food transported by phloem can be stored in specific organs for later use. Seeds and roots are primary storage sites where nutrients like starch are accumulated. Other parts listed either do not store food or have different primary functions.

Key Concept: Photosynthesis Site

b) Leaves
[Solution Description]
The syllabus states that leaves are the primary site for photosynthesis, which is the process of food preparation in plants. This is explicitly mentioned in the "Transport of food" section.

Key Concept: Phloem Function

c) Phloem
[Solution Description]
The phloem is responsible for transporting food prepared by photosynthesis in the leaves to all parts of the plant. This is clearly mentioned in the syllabus under "Transport of food" section.

Key Concept: Photosynthesis, Chlorophyll, Starch Testing

b) Brownish-yellow coloration
[Solution Description]
The covered part of the leaf does not receive sunlight, which is necessary for photosynthesis. Without photosynthesis, no starch is produced in this region. When tested with iodine, the absence of starch means the covered part will remain brownish-yellow (iodine color) rather than turning blue-black.

Key Concept: Photosynthesis - Role of Carbon Dioxide

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that carbon dioxide is essential for photosynthesis, which is true because it is one of the key raw materials required for the process. The reason explains that carbon dioxide is converted into glucose during photosynthesis, which is also true and correctly explains why carbon dioxide is essential—it provides the carbon atoms needed to form glucose.

Key Concept: Gas Exchange, Stomata, Photosynthesis

c) Entry of carbon dioxide into leaves
[Solution Description]
Stomata are responsible for gas exchange, primarily allowing carbon dioxide to enter the leaf for photosynthesis. Blocking stomata would immediately restrict CO\textsubscript{2} intake, preventing the Calvin cycle (dark reactions) from proceeding, even if light-dependent reactions continue temporarily.

Key Concept: Storage of Food

c) Seeds and roots
[Solution Description]
As per the syllabus, transported food may also be stored in seeds and roots. Phloem carries the food to these storage sites.

Key Concept: Transport Tissues

d) Xylem transports water, and phloem transports food.
[Solution Description]
Xylem transports water and dissolved minerals from roots to leaves, while phloem transports food (like sucrose) from leaves to other plant parts. Both tissues work together but have distinct functions. Option 4 accurately describes their roles.

Key Concept: Site of Photosynthesis

c) Leaves
[Solution Description]
The syllabus states that leaves are the primary site for photosynthesis, where food is prepared and later transported via phloem.

Key Concept: Respiration in Plants, Photosynthesis

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
In the given experiment, the lime water turns milky due to the presence of carbon dioxide released by germinating seeds during respiration. This confirms that plants, like animals, respire. The word equation provided in the reason accurately describes the respiration process, where glucose is broken down in the presence of oxygen to produce carbon dioxide, water, and energy. Therefore, both the assertion and reason are correct, and the reason logically explains the assertion.

Key Concept: Respiration in Plants

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that germinating seeds turn lime water milky due to the production of carbon dioxide during respiration. This is true, as demonstrated by Activity 10.8, where the lime water connected to the flask containing germinating seeds turns milky, confirming the release of carbon dioxide.
The reason explains that carbon dioxide is produced when glucose is broken down in the presence of oxygen during respiration, which aligns with the respiration equation: $Glucose + Oxygen \rightarrow Carbon\ dioxide + Water + Energy$. This is also true and correctly explains why the assertion occurs—because respiration leads to carbon dioxide production, which reacts with lime water.
Thus, both the assertion and reason are true, and the reason correctly explains the assertion.

Key Concept: Respiration vs Photosynthesis, Experimental Design

c) To supply water for germination; dry cotton would halt respiration
[Solution Description]
Moist cotton provides water necessary for seed germination and enzymatic reactions during respiration. Dry cotton would inhibit germination and respiration, leading to no CO$_2$ production and thus no change in lime water.

Key Concept: Respiration in Non-Green Parts

c) Both green and non-green parts of the plant.
[Solution Description]
All living parts of a plant, including both green (leaves) and non-green (roots, stems, flowers) parts, carry out respiration. This is because all living cells require energy, which is obtained through respiration.

Key Concept: Respiration in Plants

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
[Solution Description]
The assertion states that moong bean seeds produce carbon dioxide when soaked overnight and kept in a flask. This is true as per the syllabus, where the experimental setup demonstrates that lime water turns milky due to the presence of carbon dioxide produced by the seeds during respiration.
The reason states that carbon dioxide production by seeds indicates plant respiration, where glucose is broken down to release energy. This is also true as per the syllabus, which explicitly describes the respiration process in plants. Moreover, the reason correctly explains the assertion, as carbon dioxide production is direct evidence of respiration.
Therefore, both Assertion and Reason are true, and Reason correctly explains the Assertion.

Key Concept: Plant respiration, Energy production

d) To generate energy for growth
[Solution Description]
Respiration breaks down glucose in the presence of oxygen to release energy, which is used for various life processes such as growth, repair, and nutrient transport. The byproducts are carbon dioxide and water, but the main goal is energy production for cellular activities.

Key Concept: Respiration word equation, Non-green parts of plants

d) Equal in all parts
[Solution Description]
All parts of a plant (green or non-green) respire, but the rate depends on metabolic activity. Non-green parts like roots, stems, and seeds often have high respiration rates due to active growth or storage processes. However, if cellular activity is equal, the rate remains uniform. The question assumes equal activity, so no part has a higher rate than others.

Key Concept: Respiration in Plants

d) Assertion is false, but Reason is true.
[Solution Description]
The assertion states that respiration occurs only in leaves, which is false because all parts of a plant, including non-green parts like roots and stems, carry out respiration. The reason claims that only green parts respire due to the presence of chlorophyll, which is also false. Respiration is independent of chlorophyll and occurs in all cells for energy production. Thus both Assertion and Reason are false. However, the options provided do not include "Both Assertion and Reason are false," so the closest correct option is where the Assertion is false but the Reason is true or vice versa. Here, both are false, but since the options are limited, none directly fit. However, according to the given options, the best possible choice based on standard assertion-reason logic would be that the Assertion is false, but the Reason is not entirely accurate either, but the closest option is: Assertion is false, but Reason is true.

Key Concept: Respiration Products

c) Oxygen
[Solution Description]
Respiration produces carbon dioxide, water, and energy. Oxygen is not a product but a reactant in the process. Thus, oxygen is NOT a product of respiration.