Photosynthesis In Higher Plants

Answer (b) Grana

The number of chlorophyll molecules in a quantasome is (about ).

Answer (d) Plastocyanin

Answer (b) Bundle sheath cells

Photolysis of water requires light and chlorophyll

In plants, the first stable product formed during dark reaction is -phosphoglyceric acid. Since, it is a -carbon compound hence, the pathway is referred as pathway. Oxaloacetic acid is the first stable compound in plants. It is a compound. This acid is converted to another acid malic acid which enters into the chloroplast of bundle sheath cells.
In cycle, is phosphorylated into -diphosphoglyceric acid, which is reduced into 3-phosphoglyceraldehyde.

Sunflower does not show HSK pathway.

Answer (c) red and blue

Step 1: Understanding the term “functional unit of nature”.
The functional unit of nature refers to the smallest natural system in which living organisms interact with each other and with the physical environment.
Step 2: Role of an ecosystem.
An ecosystem includes biotic components (plants, animals, microorganisms) and abiotic components (air, water, soil), and allows energy flow and nutrient cycling.
Step 3: Analysis of options.
(A) Ecosystem: Correct — it is the basic structural and functional unit of nature.
(B) Food chain: Incorrect — it represents only a pathway of energy transfer.
(C) Ecology: Incorrect — it is the study of ecosystems, not a unit.
(D) Food web: Incorrect — it is a network of food chains within an ecosystem.
Step 4: Conclusion.
The functional unit of nature is the ecosystem.

Step 1: Understanding photorespiration in C4 plants.
In C4 plants, photorespiration involves the loss of some fixed carbon dioxide due to the process in which oxygen competes with carbon dioxide in the Calvin cycle. Typically, about one-quarter of the photosynthetically fixed CO2 is released back to the atmosphere.
Step 2: Analyzing the options.
(A) 1/6: Incorrect. This is a lower value and does not match the proportion observed in C4 plants.
(B) 2/3: Incorrect. C4 plants lose less CO2 compared to this value.
(C) 1/4: Correct. In C4 plants, approximately 1/4 of the fixed CO2 is lost to photorespiration.
(D) 5/6: Incorrect. This is too high of a value compared to the actual photorespiration rate in C4 plants.
Step 3: Conclusion.
The correct answer is (C) 1/4, as this is the proportion of CO2 released back to the atmosphere due to photorespiration in C4 plants.

Step 1: Understanding the process of photosynthesis.
Photosynthesis is a process in which plants use light energy to convert carbon dioxide and water into glucose and oxygen. The oxygen produced is a result of the splitting of water molecules during the light-dependent reactions.
Step 2: Analyzing the options.
(A) light: Light provides the energy required for photosynthesis, but it is not the source of the oxygen evolved.
(B) chlorophyll: Chlorophyll is involved in capturing light energy but is not directly responsible for the oxygen produced.
(C) CO\textsubscript{2:} Carbon dioxide is involved in the formation of glucose, not in the release of oxygen.
(D) water: Correct — Water is the source of oxygen in photosynthesis, as it is split during the light-dependent reactions to release oxygen.
Step 3: Conclusion.
The correct answer is (D) water, as oxygen is released from water molecules during photosynthesis.

Step 1: Understanding resistant varieties.
Crop varieties are developed to resist specific pests or diseases.
Step 2: Checking each pair.
Pusa Shubhra is resistant to curl blight and black rot.
Pusa Sawni and Pusa A4 are resistant to shoot and fruit borer.
Pusa Gaurav shows resistance to aphids.
Step 3: Identifying the incorrect match.
Pusa sadabahar is not resistant to both stem borer and aphids as stated.
Step 4: Conclusion.
Therefore, option (C) is the wrong match.

Step 1: Understanding stress response.
During stressful situations, the body shows a fight-or-flight response mediated by adrenal hormones.

Step 2: Hormone involved.
Adrenal medulla secretes catecholamines (adrenaline and noradrenaline) which increase heart rate, sweating, and alertness.

Step 3: Conclusion.
Therefore, these symptoms are due to increased secretion of catecholamines.

Step 1: Understanding neurogenic heart.
A neurogenic heart is one in which the heartbeat is initiated and controlled by nervous impulses rather than originating within the heart muscle itself.
Step 2: Source of contraction stimulus.
In neurogenic hearts, contraction begins only when a nerve impulse reaches the cardiac muscle. This type of heart is commonly seen in arthropods like insects.
Step 3: Elimination of incorrect options.
Elastin and collagen are structural proteins and do not generate impulses.
Muscle fibres contract but do not initiate impulses in neurogenic hearts.
Step 4: Conclusion.
The stimulus for contraction in a neurogenic heart comes from nerve fibres.

Step 1: Understanding AIDS.
AIDS (Acquired Immuno Deficiency Syndrome) is caused by HIV, which attacks the immune system, especially CD4 T-lymphocytes. The progression of the disease varies among individuals.

Step 2: Evaluating the options.
(A) AIDS does not spread through casual contact such as touching or sharing food.
(B) AIDS is not easily curable; it can only be managed with antiretroviral therapy.
(C) Some HIV-infected individuals, known as non-progressors, develop AIDS very slowly or may never develop it due to strong immune responses.
(D) HIV is not transmitted through insect bites.

Step 3: Conclusion.
The correct statement is (C), as it accurately describes the condition of non-progressors.

Step 1: Understanding the Calvin cycle steps.
The Calvin cycle involves four key steps: carboxylation (incorporation of CO2), reduction (conversion of 3-PGA to G3P), synthesis (synthesis of glucose), and regeneration (regeneration of RuBP).
Step 2: Analyzing the options.
(A) Carboxylation – reduction – synthesis – regeneration: Incorrect. This sequence does not correctly represent the Calvin cycle.
(B) Carboxylation – reduction – synthesis – regeneration: Correct. This is the correct sequence of steps in the Calvin cycle.
(C) Reduction – carboxylation – synthesis – regeneration: Incorrect. Carboxylation occurs before reduction in the Calvin cycle.
(D) Carboxylation – synthesis – regeneration – reduction: Incorrect. Synthesis occurs after reduction, not before.
Step 3: Conclusion.
The correct answer is (B) Carboxylation – reduction – synthesis – regeneration, as it is the correct sequence of steps in the Calvin cycle.

Step 1: Understanding mortality.
Mortality refers to the number of individuals dying in a population during a given time period.

Step 2: Identifying correct parameter.
Deaths directly represent mortality, while births, immigration, and emigration relate to population growth or movement.

Step 3: Conclusion.
Hence, mortality is assessed by deaths.

Step 1: Understanding sunlight utilization.
Only a small fraction of the sunlight that reaches the Earth's atmosphere is actually used for photosynthesis. This energy is absorbed by plants and used to convert carbon dioxide and water into glucose and oxygen.
Step 2: Analyzing the options.
(A) 0.05%: Incorrect, this value is slightly higher than the actual percentage used in photosynthesis.
(B) 0.02%: Correct, only about 0.02% of the total solar energy reaching the Earth is used by plants for photosynthesis.
(C) 10%: Incorrect, this is far too high compared to the actual amount used for photosynthesis.
(D) 0.2%: Incorrect, while this is closer, it is still higher than the actual percentage.
Step 3: Conclusion.
The correct answer is (B) 0.02%, as only this small fraction of sunlight is utilized for photosynthesis.

Step 1: Understanding germ layers.
In embryonic development, three primary germ layers are formed: ectoderm, mesoderm, and endoderm. Different tissues originate from these layers.
Step 2: Origin of epithelial tissue.
Epithelial tissue can arise from all three germ layers.
Ectoderm forms epidermis, mesoderm forms linings of blood vessels, and endoderm forms epithelial lining of digestive and respiratory tracts.
Step 3: Evaluation of options.
(A) Muscular: Incorrect — mainly derived from mesoderm.
(B) Epithelial: Correct — originates from ectoderm, mesoderm, and endoderm.
(C) Nervous: Incorrect — derived from ectoderm only.
(D) Connective: Incorrect — derived from mesoderm.
Step 4: Conclusion.
The tissue that originates from all three germ layers is epithelial tissue.

Step 1: Understanding the type of twins.
Identical twins are monozygotic, meaning they develop from a single fertilized ovum (zygote) that splits into two embryos.
Step 2: Analyzing the triplet condition.
Since two babies are identical twins, they originate from one fertilized ovum.
The third baby (female) must have developed from a separate fertilized ovum.
Step 3: Counting fertilized ova.
One ovum produced the identical twins and one ovum produced the third baby.
Step 4: Conclusion.
Therefore, the total number of ova fertilized is two.

Step 1: Understanding types of soil water.
Soil water exists in different forms such as gravitational, capillary, hygroscopic, and combined water.
Step 2: Availability to plants.
Only capillary water is available to plants. Hygroscopic and combined water are held too tightly to be absorbed by plant roots.
Step 3: Analysis of options.
(A) Correct statement.
(B) Incorrect — hygroscopic and combined water are not available to plants.
(C) Correct statement.
(D) Correct statement.
Step 4: Conclusion.
The incorrect statement is option (B).

Step 1: Understanding complete sex linkage.
Complete sex linkage refers to traits controlled by genes located on the X chromosome that do not have corresponding alleles on the Y chromosome and show no recombination.
Step 2: Evaluating the options.
(A) Total colour blindness: Incorrect — commonly cited as sex-linked but not used as a classic example of complete sex linkage in this context.
(B) Retinitis pigmentosa: Incorrect — may be sex-linked but not strictly complete.
(C) Myopia: Correct — cited as an example of complete sex linkage.
(D) Nephritis: Incorrect — not a sex-linked trait.
Step 3: Conclusion.
The correct example of complete sex linkage is myopia.

Step 1: Understanding anaerobic respiration.
Anaerobic respiration occurs in the absence of oxygen and mainly involves the process of glycolysis.
Step 2: ATP generation during glycolysis.
ATP is produced by substrate-level phosphorylation at two distinct steps during glycolysis.
Step 3: Analysis of options.
(A) Two steps: Correct — ATP formation occurs at two steps in glycolysis.
(B) Four steps: Incorrect — ATP is consumed at some steps.
(C) Single step: Incorrect — ATP is formed more than once.
(D) Three steps: Incorrect — only two ATP-generating steps exist.
Step 4: Conclusion.
In anaerobic respiration, ATP formation from one glucose molecule takes place at two steps.

Step 1: Understanding C pathway.
In C plants, carbon fixation occurs through the Calvin cycle.
Step 2: CO acceptor.
Ribulose-1,5-bisphosphate (RuBP) acts as the primary acceptor of atmospheric CO in C plants.
Step 3: Conclusion.
Therefore, the correct answer is RuBP only.

Step 1: Understanding HSK (C ) pathway.
In C plants, malate is transported from mesophyll cells to bundle sheath cells.
Step 2: Reaction in bundle sheath.
Malate undergoes decarboxylation to release CO , which enters the Calvin cycle.
Step 3: Conclusion.
Hence, malate undergoes decarboxylation.

Step 1: Understanding photorespiration.
Photorespiration occurs when oxygen (O2) competes with carbon dioxide (CO2) for binding to Rubisco in plants. This typically happens when temperatures are high, light intensity is high, and CO2 levels are low.
Step 2: Analyzing the options.
(A) temperature is high, light intensity is high and CO2 concentration is low: Correct — This is the condition that promotes photorespiration, leading to the oxidation of RUBP by O2.
(B) temperature is low, light intensity is low and CO2 concentration is low: Incorrect — This combination does not favor photorespiration.
(C) temperature is low, light intensity is high and CO2 concentration is low: Incorrect — Though light intensity is high, low temperature and low CO2 concentration are not conducive to photorespiration.
(D) temperature is high, light intensity is high and CO2 concentration is high: Incorrect — High CO2 concentration prevents photorespiration by allowing Rubisco to fix CO2, not O2.
Step 3: Conclusion.
The correct answer is (A) temperature is high, light intensity is high and CO2 concentration is low, as this condition leads to photorespiration.

Step 1: Understanding NADPH formation.
During the light reaction of photosynthesis, NADP is reduced to NADPH . This reduction requires the transfer of electrons as well as protons (H ions).
Step 2: Analyzing the options.
(A) only protons: Incorrect. Protons alone cannot reduce NADP .
(B) only electrons: Incorrect. Both electrons and protons are required.
(C) neither protons nor electrons: Incorrect. Reduction cannot occur without them.
(D) protons along with electrons: Correct. NADP accepts both electrons and protons to form NADPH .
Step 3: Conclusion.
The correct answer is (D) protons along with electrons.

Step 1: Understanding ecological pyramids.
Ecological pyramids represent the number, biomass, or energy at each trophic level.
Step 2: Biomass in aquatic ecosystems.
In marine ecosystems, producers (phytoplankton) have less biomass compared to consumers (zooplankton and fishes).
Step 3: Resulting pyramid shape.
Due to low standing crop of producers, the biomass pyramid in sea becomes inverted.

Concept:
Chlorophyll is a green pigment found in the chloroplasts of plant cells and is essential for the process of photosynthesis. It plays a key role in absorbing light energy, primarily from the blue and red regions of the electromagnetic spectrum, and converting it into chemical energy that fuels plant growth.

The structure of a chlorophyll molecule is complex and consists of a porphyrin ring (similar to the structure of heme in blood), with a centrally coordinated magnesium ion (Mg²⁺).

Key Elements in Chlorophyll Complex:
1. Carbon (C) – forms the backbone of the porphyrin ring and the phytol tail.
2. Hydrogen (H) – involved in various functional groups and in the phytol chain.
3. Oxygen (O) – present in side chains and involved in structural stability.
4. Nitrogen (N) – four nitrogen atoms coordinate around the central metal ion, forming the core of the porphyrin ring.
5. Magnesium (Mg) – the central atom in the porphyrin ring that is crucial for capturing light energy.

Why Magnesium is Important:
• Magnesium acts as the central metal ion and binds to the nitrogen atoms in the ring structure.
• It plays a vital role in light absorption and energy transfer during photosynthesis.

Conclusion:
The primary elements that form the chlorophyll complex are carbon, hydrogen, oxygen, nitrogen, and magnesium. Each of these elements contributes to the structure and function of the molecule, enabling plants to carry out photosynthesis efficiently.

Reproduction in plants can be broadly classified based on their evolutionary advancement, with higher plants and lower plants employing distinct methods of reproduction. Step 1: Reproduction in Lower Plants.
Lower plants, which include algae, bryophytes (mosses), and pteridophytes (ferns), primarily reproduce through spores. Spores are: Single-celled reproductive units that can develop into new individuals without the need for fertilization. Produced in large quantities to increase the likelihood of successful dispersal across the environment. Primarily adapted to moist environments, where they can germinate and grow effectively. For example, ferns release spores that can germinate into gametophytes, which will then produce gametes for fertilization. Step 2: Reproduction in Higher Plants.
Higher plants, which include gymnosperms (e.g., pine trees) and angiosperms (flowering plants), reproduce through seeds. Seeds are: Multicellular structures containing a young plant embryo, stored food, and a protective seed coat. Produced following sexual reproduction, where male and female gametes (sperm and egg cells) fuse to form a zygote that eventually develops into a seed. Adapted to survive in various terrestrial environments and are capable of dormancy, allowing them to withstand unfavorable conditions until they can germinate. The production of seeds allows for better survival in diverse environments and enhances the dispersal capabilities of plants. Step 3: Comparing Reproduction Methods.
To compare the methods: Lower plants: They predominantly rely on spores, which are single-celled and used for asexual reproduction. Spores require moist conditions for successful germination. Higher plants: They reproduce through seeds, which are multicellular and produced through sexual reproduction, making them better suited for survival in a wider range of environments. Thus, the correct statement is: Thus, the correct answer is .

Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose. It occurs in two main stages: the light reactions and the Calvin cycle (dark reactions). The light reactions take place in the thylakoid membranes of the chloroplasts, and they involve the capture of light energy by chlorophyll. This energy is used to produce ATP and NADPH, which are then used in the Calvin cycle to fix carbon and produce glucose. Now, let's break down the options: 1. A) Calvin cycle: The Calvin cycle, also known as the dark reactions or light-independent reactions, occurs in the stroma of the chloroplasts. It uses the products of the light reactions, namely ATP and NADPH, to fix carbon dioxide and form glucose. However, it does not directly produce oxygen. Oxygen is produced during the light reactions, not the Calvin cycle. 2. B) Photolysis of water: Photolysis of water is the process during the light reactions where water molecules are split into oxygen, protons (H ), and electrons (e ) by the energy absorbed from light. This reaction occurs in the thylakoid membranes and is crucial for the production of oxygen during photosynthesis. The oxygen atoms released in this process are the source of the oxygen gas that is released into the atmosphere as a byproduct of photosynthesis. The overall equation for photolysis is: This is the direct source of the oxygen produced during photosynthesis. 3. C) Cyclic photophosphorylation: In cyclic photophosphorylation, electrons flow in a cycle through the photosystem I, resulting in the production of ATP, but not NADPH or oxygen. Since no photolysis of water occurs in this process, oxygen is not produced. 4. D) Reduction of NADP+: The reduction of NADP+ to NADPH occurs during the light reactions, specifically in non-cyclic photophosphorylation. This process is important for the subsequent steps of the Calvin cycle, but it does not produce oxygen. Oxygen is produced during photolysis of water, not during the reduction of NADP+. Therefore, the correct answer is B) Photolysis of water, as this is the process directly responsible for the production of oxygen during photosynthesis.

Chlorophyll is a pigment found in the chloroplasts of plant cells. It plays a key role in photosynthesis by absorbing light, particularly in the blue and red wavelengths. The energy absorbed by chlorophyll is used to convert carbon dioxide and water into glucose and oxygen. This process is essential for producing the chemical energy that plants need for growth and development. Thus, chlorophyll absorbs light energy and converts it into chemical energy, which is then used in the synthesis of glucose.