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CBSE Questions for Class 11 Medical Biology Photosynthesis In Higher Plants Quiz 6 - MCQExams.com
CBSE
Class 11 Medical Biology
Photosynthesis In Higher Plants
Quiz 6
$$NH_{3}$$ releases during which of the following process?
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Photorespiration
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Dark respiration
0%
CAM
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All of the above
Explanation
Photorespiration is a wasteful process, which occurs in $$C_3$$ plants in presence of light. In the photorespiratory pathway, there is neither synthesis of sugars, nor of ATP. Rather it results in the release of $$CO_2$$ with the utilisation of ATP.
In the photorespiratory pathway there is no synthesis of ATP or NADPH. Therefore, photorespiration is a wasteful
process. This process occurs in chloroplast, peroxisomes and mitochondria. In mitochondria two molecules of glycine combine together to form a molecule of serine, with the simultaneous release of carbon dioxide and ammonia.
Which of the following acts as electron carrier in both photosynthesis and respiration?
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F$$_1$$ region
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Phytochrome
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Cytochrome
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Cryptochrome
Explanation
Cytochrome acts as an electron carrier in both photosynthesis and respiration. Cytochromes are, thus, capable of performing oxidation and reduction. Because the cytochromes (as well as other complexes) are held within membranes in an organized way, the redox reactions are carried out in the proper sequence for maximum efficiency.
Whereas, phytochromes and cryptochromes are photoreceptors, having different functions.
F$$_1$$ region is part of the ATP synthase complex and hydrolyzes ATP.
Therefore, the correct answer is option C.
Chemiosmotic theory of ATP synthesis in the chloroplast and mitochondria is based on
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Proton gradient.
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Accumulation of K
$$^+$$
ions.
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Accumulation of Na$$^+$$ ions.
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Membrane potential.
Explanation
According to the chemiosmosis theory of ATP generation. The ATP is generated utilizing the electrochemical gradient generated due to the accumulation of protons in the thylakoid lumen of chloroplast or peri-mitochondrial space in mitochondria.
The accumulation of protons gives rise to an electric gradient, due to the accumulation of positive charge and a chemical gradient due to the accumulation of hydrogen atom. When protons move along this electrochemical gradient through $$F_0$$-$$F_1$$ ATP synthase enzyme complex, ATP generation occurs.
Sugarcane shows a higher efficiency of
C
O
2
CO2
fixation because of
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Calvin cycle.
0%
Hatch and Slack cycle.
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TCA Cycle.
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Greater sunlight.
Explanation
Tropical grasses like sugarcane, sorghum etc. are $$C_4$$ plants. They fix carbon dioxide by Hatch and Slack cycle. These plants do not show photorespiration and are hence better photosynthesizers than $$C_3$$ plants. These plants have kranz anatomy.
These plants have a special ring of thick walled bundle sheath cells around vascular bundle. The bundle sheath cells lack intercellular spaces. They have large chloroplasts without grana. In the bundle sheath cells carbon dioxide is fixed by the enzyme RuBisCO. After carbon dioxide fixation by RuBisCO, Calvin cycle proceeds as in $$C_3$$ plants. The mesophyll cells are the usual cell type as found in $$C_3$$ plants also. Initial carbon dioxide fixation into organic acids occurs in the mesophyll cells. These organic acids are transported to bundle sheath cells through plasmodesmata. In bundle sheath cells they are decarboxylated to release carbon dioxide, which is fixed using RuBisCO and normal Calvin cycle takes place.
The primary acceptor during CO$$_2$$ fixation in the C$$_3$$ plants is
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Ribulose biphosphate.
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Glycolate.
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Phosphoenolpyruvate.
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Triose phosphate.
Explanation
The dark reaction of the photosynthesis takes place mainly in the stroma of the chloroplast. C$$_3$$ carbon fixation is one of three metabolic pathways for carbon fixation in photosynthesis, along with C$$_4$$ and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into 3-phosphoglycerate through the following reaction:
CO$$_2$$ + RuBP → (2) 3- phosphoglycerate
This reaction occurs in all plants as the first step of the Calvin-Benson cycle.
So, the correct answer is option A.
The first stable compound in the C$$_3$$ cycle is
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Phosphoglyceraldehyde.
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Phosphoglyceric acid.
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Fructose - 1 - 6 diphosphate.
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Glucose - 6 - phosphate.
Explanation
The first stable compound in Calvin cycle is a 3 carbon compound namely 3 phosphoglyceric acid (PGA). Hence the Calvin cycle is also called as C$$_3$$ cycle.
Besides leucoplasts starch grains are developed in:
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chromoplasts
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chloroplasts
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mitochondria
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lysosomes
The assimilatory power in photosynthesis is
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ATP
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NADPH
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ATP and NADPH$$_2$$
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ATP, NADPH and CO$$_2$$
Explanation
Photosynthesis is an important physiological process that takes place in the chloroplast of the green plants wherein sugar is synthesized from water and carbon dioxide in the presence of light. This is also referred to as carbon assimilation reaction as this oxidation- reduction process involves a light reaction and dark reaction where water is oxidized and CO$${_2}$$ is reduced to carbohydrates. In light reaction, ATP and NADPH
$${_2}$$
are produced and in the dark reaction, CO
$${_2}$$
is reduced with the help of ATP and NADPH
$${_2}$$
to produce glucose.
So, the correct answer is '
ATP and NADP$$H_2$$
Dark reaction, in photosynthesis is called so because
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It does not require light energy.
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It can not occur during daytime.
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It occurs more rapidly at night.
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It can also occur in darkness.
Explanation
Dark reactions do not need light. Instead, dark reaction uses ATP and NADPH to produce energy molecules. No photosystem is required. Photolysis of water does not occur. So, the dark reaction in photosynthesis is called so because it does not require light energy.
This process occurs in dark reaction
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$$H^{+}$$ is taken by a hydrogen acceptor NADP
0%
Photolysis of water
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Formation of $$NADPH_{2}$$
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$$CO_{2}$$ is reduced
Explanation
In Dark reaction or biosynthetic phase, $$CO_{2}$$ is reduced (with the help of $$NADPH_{2}$$ and ATP produced in the light reaction) to glucose with the help of enzymes present in stroma of chloroplast.
Which of the following reaction takes place inside stroma of chloroplasts where light energy is not captured?
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Light
0%
Both dark and light
0%
Krebs
0%
Dark
Explanation
Photosynthesis is divided into two sets of reactions: the light-dependent (light) reactions and the light-independent (dark) reactions. The light reactions, which convert the energy in light into chemical energy, take place within the thylakoid membranes of the chloroplasts, whereas the dark reactions, which use that chemical energy to fix $$CO_2$$ into organic molecules, take place in the stroma of the chloroplast.
Dark reaction and light reaction of photosynthesis takes place in the
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Stroma and grana of chloroplast respectively
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Grana and stroma of chloroplast respectively
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Grana only
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Stroma only
Explanation
Photosynthesis takes place in two major steps, light reaction, and dark reaction.
Carbon-fixing during the dark reaction (light-independent process) takes place in the stroma of the chloroplast.
The light reactions of photosynthesis occur in the thylakoids of grana present in the chloroplast.
So, the correct answer is option A.
Which enzyme is most abundantly found on earth?
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Rubisco
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Nitrogenase
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Invertase
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Catalase
Explanation
Rubisco is the critical enzyme that catalyzes the addition of CO$$_2$$ to ribulose- 1, 5- bisphosphate during the Calvin cycle. It is the most abundant enzyme on earth.
So, the correct answer is option A.
(1 point) In the electron transport chain in mitochondria, several proteincomplexes traverse the mitochondrial inner membrane. Mark the figure that shows correct topology of these complexes.
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0%
0%
0%
Dark reaction in photosynthesis is called so because
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It does not require light energy.
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Cannot occur during daytime.
0%
Occurs more rapidly at night.
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It can also occur in darkness.
Explanation
Dark reactions do not need light. Instead, dark reaction uses ATP and NADPH$$_2$$ to produce energy molecules. No photosystem is required. Photolysis of water does not occur. The dark reaction in photosynthesis is called so because it does not require light energy.
So, the correct answer is option A.
The most abundant enzyme found on the earth is
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Nitrogenase.
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Invertase.
0%
Rubisco.
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Catalase.
Explanation
The enzyme ribulose- 1, 5- bisphosphate carboxylase/oxygenase is most commonly known by the name RuBisCO and is used in the Calvin cycle to catalyze the first major step of carbon fixation. RuBisCO is thought to be the most abundant protein in the world since it is present in every plant that undergoes photosynthesis and molecular synthesis through the Calvin cycle.
So, the correct answer is option C.
Photosynthetic pathway which occurs in tropical grass plants is
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Hill Reaction.
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Calvin Cycle.
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Blackman reaction.
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Hatch and Slack cycle.
Explanation
Hatch and slack cycle takes place in C4 plants. In these plants, there are two types of cells namely mesophyll cells and bundle sheath cells. Carbohydrate, the end product is synthesised in bundle sheath cells. C4 plants have high photosynthetic efficiency due to their ability to fix carbon dioxide in environmental conditions where its concentration is less hence seen in tropical grass plants. Thus the correct answer is option D.
Select the wrongly matched option.
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Core elements of - magnesium chlorophyll
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Initial carbon acceptor - phosphoenol in C$$_4$$ cycle pyruvate
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Photorespiration - C$$_4$$ cycle
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Passive mechanism - water absorption by roots
Which one is wrong about photosynthesis?
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30 APT and 18 NADPH + $$H^+$$ are needed for $$C_3$$ and $$C_4$$ cycles.
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water provides source of hydrogen for $$CO_2$$ reduction and evaluation of molecular oxygen.
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Light and light reaction products are necessary for dark reaction
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Oxygenase property of RuBisCO is the reason for photorespiration in $$C_3$$ plants.
Explanation
In the process of photosynthesis, The C3 pathway requires 18 molecules of ATP and the C4 pathway requires 30 molecules of ATP. While 12 NADPH molecules are required in the C4 cycle and 12 are required for C3 cycle in case of photosynthesis.
All other given statements hold true for the process of photosynthesis.
So, option A is the incorrect statement and correct answer.
The dark reaction of photosynthesis occurs in the
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Stroma of the chloroplast outside the lamellae.
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Space between the two membranes of the chloroplast.
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Membranes of the stroma lamellae.
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Thylakoid membrane of the grana.
Explanation
The
dark reaction of photosynthesis takes place in the s
troma of the chloroplasts as the enzymes of stroma do not require light but require ATP and NADPH$${_2}$$
produced in the light reaction. It is also known as light independent reaction.
So, the correct answer is option A.
In plant cells, peroxisomes are associated with
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Photorespiration.
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Phototropism.
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Photoperiodism.
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Photosynthesis.
Explanation
Photorespiration is a process in which, during water stress conditions, oxygen starts inhibiting Calvin cycle. Photorespiration takes place in the chloroplast, peroxisomes and mitochondria. In the first step in chloroplasts, glycolate is formed which enters peroxisomes where oxygen is converted into hydrogen peroxide and glycine is formed which enters mitochondria where carbon dioxide is released.
Site of ATP synthesis in the cell is _______.
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Outer mitochondrial membrane
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Mitochondrial matrix
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Cristae
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None of the above
During what stage of photosynthesis are NADP$$^+$$ and ADP$$^+$$ Pi converted to ATP and NADPH?
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The ligh dependent reactions
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The light independent reactions
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Both (A) and (B)
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None of the above
Explanation
During the light phase of photosynthesis, ATP and NADPH are synthesised from ADP and NADP which become the assimilatory power for dark phase reactions to fix and reduce carbon dioxide.
Dark reaction of photosynthesis occurs in
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Thylakoid membrane
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Membranes of stroma lamellae
0%
Between two membranes of chloroplast
0%
Stroma of chloroplast outside lamellae
Explanation
The
dark reaction of photosynthesis takes place in the s
troma of the chloroplast. The enzymes of stroma which are present outside the grana lamellae do not require light but require ATP and NADPH$$_2$$
produced in the light reaction. It is also known as light independent reaction.
Thus, the correct answer is option A.
Which of the following cell organelles is associated with photorespiration?
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Mitochondria
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Peroxysome
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Chloroplast
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All of the above
Explanation
Photorespiration is a special type of respiration shown by many green plants when they are exposed to light.
It involves three organelles chloroplast, perioxisomes and mitochondria.
In the chloroplast, phosphoglycolate is unstable and is converted to glycolate. PGA is used up in the calvin cycle. The peroxisomes present in the cell convert the glycolate into glyoxylate and then into glycine. Glycine is converted to serine and CO
2
in the mitochondria. The serine thus formed is converted to glycerate, through a series of reactions which occurs in the peroxisome. Hence, option D is correct.
In $${C_4}$$ plants, the first carbon dioxide acceptor is ..........
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Pyruvate
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Phosphoenol pyruvate
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Ribulose Bisphosphate
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Ribulose 5 - phosphate
Explanation
C$$_4$$ cycle also known as Hatch and Slack cycle operates in C$$_4$$ plants wherein the primary CO$$_2$$ acceptor is 3C compound, Phosphoenolpyruvate (PEP) and first stable product formed is a 4-carbon compound, oxalo acetic acid (OAA). Hence, option B is correct.
The specific characteristic of $${C}_{4}$$ plants is
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Isobilateral leaf.
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Tap root.
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Parallel venation.
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Kranz anatomy.
Explanation
Kranz anatomy refers to an arrangement of bundle sheath cells surrounded by mesophyll cells in $$C_4$$ plants. This arrangement allows the transport of $$C_4$$ cycle metabolites via plasmodesmata through these two cell types. It can occur in both monocot and dicots.
Thus, the correct option is D.
Which of the following characteristics are exhibited by
C
4
C4
plants?
I. Kranz anatomy.
II. The first product of photosynthesis is oxaloacetic acid.
III. Both PEP carboxylase and ribulose biphosphate carboxylase acts as carboxylating enzymes.
The correct option is
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I and III, but not ll.
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I, II and III.
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II and III, but not I.
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ll and III.
Explanation
$$C_4$$
-plants have an alternative $$CO_2$$
fixation
pathway, called as Hatch and Slack cycle. These
plants have Kranz anatomy in leaf, where
vascular bundles are surrounded by bundle
sheath.
In $$C_4$$
cycle light reaction occurs in, mesophyll
chloroplast by PEP carboxylaes and the
assimilation of $$CO_2$$
takes place in, i.e., dark
phase in bundle sheath chloroplast by
Rubisco.
The family with many $$C_4$$ plants is
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Malvaceae
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Solanaceae
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Cruciferae
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Gramineae
Explanation
$$C_4$$ plants
are those which photosynthesize following the mechanism called
$$C_4$$
photosynthesis.
They are found only in the
angiosperms
with about 8,000 members in 17 families ( equivalent to about 3% of all land plants. Combined, the grasses (family Poaceae or Gramineae) and sedges (family Cyperaceae) comprise roughly 79% of the total number of
$$C_4$$
species with Gramineae family comprises highest number of
$$C_4$$
plants.
Examples of
$$C_4$$
species
are the economically important crops corn or maize (
Zea mays
), sugarcane (
Saccharum officinarum
), sorghum (
Sorghum bicolor
), and millets. Hence option D is correct.
Biosynthetic phase is also known as
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Dark reaction
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Light reaction
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Photochemical phase
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Light dependent phase
Explanation
Biosynthetic phase is also known as the dark phase of photosynthesis which does not require light to happen. It requires ATP and NADPH$${_2}$$ to fix carbon dioxide.
Which statement is correct regarding biosynthetic phase?
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It needs energy produced during the light phase.
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It does not need light directly.
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It works in both light and dark conditions.
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All of the above
Explanation
Biosynthetic phase is also known as the dark phase of photosynthesis which does not require light to happen.
It requires ATP and NADPH$${_2}$$ to fix carbon dioxide that is produced during the light phase of photosynthesis.
It takes place in the dark as well as light.
So, the correct answer is option D.
In the leaves of $$\displaystyle { C }_{ 4 }$$ plants, malic acid synthesis during $$\displaystyle { CO }_{ 2 }$$ fixation occurs in
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Bundle sheath.
0%
Mesophyll.
0%
Epidermis.
0%
Guard cells.
Explanation
$$C_4$$ plants almost never saturate with light and under hot, dry conditions much outperform $$C_3$$ plants. They use a two-stage process, where $$CO_2$$ is fixed in thin-walled mesophyll cells to form a 4-carbon intermediate, typically malate (malic acid).
The reaction involves phosphoenolpyruvate (PEP), which fixes $$CO_2$$ in a reaction catalyzed by PEP-carboxylate. It forms an oxaloacetic acid (OAA), which is quickly converted to malic acid. The 4-carbon acid is actively pumped across the cell membrane into a thick-walled bundle sheath cell where it is split to $$CO_2$$
and a 3-carbon compound.
Which of the following is true for Calvin cycle?
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Does not use light directly
0%
Occurs in the cytoplasm
0%
Releases CO$$_{2}$$
0%
Produces ATP
0%
All of the above
Explanation
Calvin cycle is the set of chemical reactions that take place in chloroplasts during photosynthesis.
The cycle is light-independent because it takes place after the energy has been captured from sunlight during the light reaction. Thus, it does not use the sunlight directly.
The steps involved in the Calvin cycle are as follows -
A five-carbon molecule called Ribulose-5-phosphate takes up one molecule of carbon dioxide and forms a six-carbon molecule (ribulose-1,5-bisphosphate). Thus, CO$$_2$$ is fixed during the Calvin cycle.
The enzyme RuBisCO with the energy of ATP and NADPH molecules breaks the six-carbon molecule into two equal parts. Thus, ATP and NADPH produced during light are utilized during the Calvin cycle.
These 3-carbon molecule moves on to the next step and undergoes reduction producing Glyceraldehyde-3-phosphate. One 3 carbon compound is involved in the formation of sugar.
Using ATP and NADPH, another three-carbon molecule (Glyceraldehyde-3-phosphate) is changed into a five-carbon molecule (Ribulose-5-phosphate) and the cycle is repeated again.
So, the correct answer is option A.
In which of the following process ATP synthase channel produces ATP?
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Glycolysis
0%
Kerbs cycle
0%
Chemiosmosis
0%
(B) and (C) only
0%
(A), (B) and (C)
Explanation
Glycolysis and Krebs cycle form total 4 ATPs by substrate level phosphorylation wherein direct transfer of phosphate group to ADP or GDP during chemical reactions leads to synthesis of ATP/GTP. Oxidative phosphorylation is the process wherein oxidation of reducing equivalent generate energy to drive ATP synthesis. Chemiosmosis includes use of proton gradient generated across the inner mitochondrial membrane, during transfer of electrons from NADH and FADH$$_2$$ to O$$_2$$, to drive ATP synthesis on ATP synthase channel. Since inner mitochondrial membrane is impermeable to protons; protons can re-enter the matrix only through proton-specific channels (F$${_0}$$) of ATP synthase only.
Therefore, the correct answer is option C.
Choose the correct sequence of electron pathway in electron transport system.
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Cyt oxidase $$\rightarrow$$ cyt reductase $$\rightarrow$$ succinic hydrogenase $$\rightarrow$$ NADH dehydrogenase
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NADH dehydrogenase $$\rightarrow$$ succinic dehydrogenase $$\rightarrow$$ cyt c reductase $$\rightarrow$$ cyt c oxidase
$$\rightarrow O_2$$
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NADH dehydrogenase $$\rightarrow$$ cyt c reductase $$\rightarrow$$ cyt c oxidase $$\rightarrow O_2$$
0%
Succinic dehydrogenase $$\rightarrow$$ cyt oxidase $$\rightarrow$$ cyt reductase $$\rightarrow O_2$$
Explanation
An electron transport chain (ETC) is a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions, and couples this electron transfer with the transfer of protons (H$$^+$$ ions) across a membrane. The pathway of electron in the electron transport system is shown in the above figure.
So, the correct option is option B
Choose the correct statement from the following.
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Stoma lamella membrane lacks PO and PS- I.
0%
When PS- I is functional electrons flow in a non cyclic way.
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ATPase enzyme consist of $$F_0$$ and $$F_1$$ units.
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NADP reductase is a part of PS- II.
Explanation
ATP synthase is an enzyme which helps in ATP synthesis. The enzyme ATP synthase has two part $$F_0$$ and $$F_1$$. $$F_0$$ is the part which transports protons across the membrane as a transmembrane channel while configuration changes in $$F_1$$ activates the enzyme. They phosphorylate ADP i.e., add one more phosphorus group to the ADP and converts ADP(adenosine diphosphate) to ATP (adenosine triphosphate). The proton gradient developed across the membrane is the driving force of ATP synthase.
Read the following statements :
a) $$F_0$$ part of ATPase is associated with breakdown of proton gradient.
b) A H - carrier contributes in creation of proton gradient.
c) Movement of electrons in ETS is coupled to pumping of protons into the lumen.
d) Formation of $$NADPH + H^+$$ is related with the creation of proton gradient.
How many of the above statements are correct ?
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Two
0%
One
0%
Four
0%
Three
Chloroplast dimorphism is a characteristic feature of
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Plants with Calvin cycle.
0%
C$$_4$$ plants.
0%
All plants.
0%
Algae only.
Explanation
In Kranz anatomy, the vascular bundle is surrounded by two rings: Inner ring is bundle sheath cell and outer ring is mesophyll cells. Bundle sheath may be single layered as in Maize or double layered as in sugarcane. If two layered, the outer one is green and the inner one is thick walled and called as mestome sheath. Mesophyll cell chloroplasts are granal and starch lacking but the bundle sheath cell chloroplasts are without grana and rich in starch. Such feature is known as chloroplast dimorphism. Dimorphism of chloroplast is found in C$$_4$$ plants. Thus, the correct answer is option B.
The products of light reaction of photosynthesis are
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ATP and NADPH.
0%
ATP and glucose.
0%
NADH and glucose.
0%
ATP and NADH.
0%
NADPH and glucose.
Explanation
The main photosynthetic pigment chlorophyll a and accessory pigments chl. b, chl. c and carotenoids etc., trap the sunlight to carry out the light reactions of photosynthesis.
The light reaction of photosynthesis produces ATP and NADPH which in turn serve as the energy source to drive the second phase of photosynthesis (dark reactions) during which carbohydrate synthesis takes place.
What is the name of cycle, which generates energy and splits water into hydrogen and oxygen?
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Glycolysis
0%
Photophosphorylation
0%
Citric acid cycle
0%
Electron transport cycle
Explanation
Photophosphorylation refers to the use of light energy to ultimately provide the energy to convert ADP to ATP, thus replenishing the universal energy currency in living things.
The light energy entering the plant splits water into hydrogen and oxygen.
H$$_2$$O + light energy -----> O $$_2$$ + 2H$$^-$$ + 2 electrons
These electrons travel through a membrane bound electron transport chain much like the electrons in oxidative phosphorylation, using their energy to pump protons through the membrane. The proton gradient thus established can be used to synthesize ATP.
The form of carbon used for the carboxylation of phosphoenol pyruvate in C$$_4$$ plants is
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$$H_2CO_3$$
0%
$$C_2H_4$$
0%
$$CH_4$$
0%
$$HCO^{-}_{3}$$
Explanation
HCO$$-3$$- reacts with the three-carbon acid phosphoenolpyruvate (PEP or PEPA, C$$_3$$H$$-5$$O$$_6$$P) to form oxaloacetate (OAA, oxaloacetic acid= C$$_4$$H$$_4$$O$$_5$$). The reaction is catalyzed by the carboxylating enzyme phosphoenolpyruvate carboxylase (PEPcase, PEPC or PEPCO). OAA is a four-carbon product, hence the term C$$_4$$ photosynthesis.
Photophosphorylation is the process in which
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Carbon dioxide and oxygen combine
0%
Phosphoglyceric acid is produced
0%
Aspartic acid is formed
0%
Light energy is converted into chemical energy through production of ATP
Explanation
Photophosphorylation is the process of light driven electron transport across a membrane wherein the resultant proton or sodium electrochemical gradient is coupled to ATP synthesis. The process involves light driven flow of electrons through a chain of membrane bound carriers which in turn generate free energy. This free energy is coupled to the uphill transport of protons across a proton-impermeable membrane to conserve the free energy as a transmembrane electrochemical potential. The free energy provided by transmembrane flow of protons down their concentration gradient drives ATP synthesis. The light energy is being converted into ATP.
Calvin cycle performs the function of
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Production of ATP.
0%
Chemical breakdown of water.
0%
Fixation of carbon.
0%
Production of oxygen gas.
0%
Absorption of light energy.
Explanation
The Calvin cycle, Calvin cycle, or reductive pentose phosphate cycle is also known as the C3 cycle a series of biochemical redox reactions that take place in the stroma of the chloroplasts during photosynthesis. These reactions are also known as light-independent reactions. While the light dependent reactions of
photosynthesis capture the energy of light and use it to make the energy storage and transport molecules ATP and NADPH, the light-independent reaction or the Calvin cycle uses the energy from short-lived electronically excited carriers and converts carbon dioxide and water into organic compounds that can be used by the organisms. The fixation of carbon is one of the main functions of the Calvin cycle.
So, the correct answer is option C.
The synthesis of ATP from ADP and inorganic phosphate is a(n) ________ reaction that is coupled to a reaction known as ________.
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Endergonic; Chemiosmosis
0%
Exergonic; Chemiosmosis
0%
Chemical; ATP synthase
0%
Chemiosmotic; ATP synthase
Explanation
Endergonic reactions are energy absorbing reactions, during the formation of ATP, iP is added to ADP using energy. So, formation of ATP is an endergonic reaction and it occurs through a process of chemiosmosis.
So, the correct answer is '
Endergonic; Chemiosmosis'
In the light reactions, light energy harvested from the sun drives the synthesis of ATP and NADPH and is coupled with the formation of
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ADP
0%
Carbon dioxide
0%
Oxygen
0%
Glucose
Explanation
Light energy harvested from the sun is used to synthesize ATP and NADPH during the light dependent reaction. Which is then used for fixing CO$$_2$$ into glucose and releasing O$$_2$$ and H$$_2$$O as byproducts
So, the correct answer is '
Glucose'
The production of ATP through chemiosmosis is known to occur in which of the following organisms?
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All cells (prokaryotic and eukaryotic) are capable of respiration using either oxygen or other electron acceptors.
0%
All cells (prokaryotic and eukaryotic), but only in the presence of oxygen.
0%
Eukaryotic cells only, and only when oxygen is present.
0%
All cells that possess mitochondria, and only when oxygen or other electron acceptors are present.
Explanation
The chemiosmotic theory explains the utilization of proton-motive force or proton gradient for formation of ATP molecules. The e$$^-$$ of the Electron Transport Chain / System are accepted by O$$_2$$ along with the protons to form water molecules and it takes place in both prokaryotic and Eukaryotic
cells where oxidation of glucose takes place in the presence of oxygen
So, the correct answer is '
All cells (prokaryotic and eukaryotic), but only in the presence of oxygen'
Select correct statement concerning plants that utilize $$C_4$$ photosynthesis.
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They only open their stomata in the day
0%
They use bundle sheath cells to separate the Calvin cycle from the atmosphere
0%
They use RuBisCO (ribulose bisphosphate carboxylase oxygenase) to capture carbon dioxide from the atmosphere
0%
They use lenticels exclusively for gaseous exchange in order to conserve water
0%
All of the above are true
Explanation
CAM plants exhibit temporal separation of photosynthesis and open stomata during night only.
In C4 plants, spatial separation of carbon dioxide fixation and
RuBisCO
activity in mesophyll and bundle sheath cells of $$C_4$$ plants respectively avoids photorespiration by concentrating $$CO_2$$ in bundle sheath cells to scale down the oxygenase activity of
RuBisCO
and increase the RuBisCO efficiency.
PEP carboxylase enzyme of mesophyll cells fixes Carbon dioxide and malate enters Calvin cycle in bundle sheath cells only.
Thus, the correct answer is B.
Plant shows adaptations to hot and dry climates is
I. CAM
II. Mycorrhizae
III. $${C}_{4}$$ photosynthesis
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0%
I only
0%
II only
0%
I and II
0%
I and III
0%
I, II, and III
Explanation
Plants have adaptations to help them survive (live and grow) in different areas. The deserts are regions with hot and dry climates all the year round. Lack of rainfall or very little rainfall makes the climate extremely dry for the survival of plants. Hence the plants adapt to this by storing water in stems, roots, or fleshy leaves and by employing CAM process. Instead of synthesizing carbohydrates, the CAM (Crassulacean Acid Metabolism) photosynthetic process synthesize Crassulacean acid during the day while their stomata are closed and store it in their tissues. At night, when temperatures are lower and humidity higher, they open their stomata and break down the acids into carbohydrates using carbon dioxide from the air. CAM is extremely efficient at using water. Further, the desert plants follow a C4 photosynthesis process where an alternative pathway of Calvin cycle takes place during the dark phase of photosynthesis
Which of the following products of the light reaction are assimilated in dark reaction?
I. Reduced NADP (NADPH)
II. ATP
III. O$$_2$$
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0%
I only
0%
II only
0%
III only
0%
I and II only
0%
I, II and III
Explanation
Splitting of water molecule during light reactions forms oxygen and the released electrons reduce NADP into NADPH. NADPH and ATP are used in dark reactions as an energy source for fixation of carbon dioxide into carbohydrates. Oxygen is the by-product of light reactions and is not consumed during dark reactions.
So, the correct answer is D.
In photosynthesis, an electrochemical gradient of hydrogen ions is established by the movement of protons into the
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0%
Stroma
0%
Thylakoid space
0%
Inner membrane
0%
Matrix
Explanation
During photosynthesis an electrochemical gradient or proton motive force is created by
release (photolysis) or
movement of protons into thylakoid lumen from the stroma. The energy released during this movement is used for the formation of ATP molecules by ATP synthase, CF$$_o$$, CF$$_1$$ particles.
The thylakoid membrane is impermeable to protons, so the protons are transported through symporter proteins, H$$^+$$/Cl$$^-$$ or by antiporter protein,$$\uparrow$$H$$^+$$/$$\downarrow$$Mg$$^{+2}$$
So, the correct answer is '
Thylakoid space'.
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Practice Class 11 Medical Biology Quiz Questions and Answers
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