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2 years ago

In photosynthetic cells, synthesis of atp by the chemiosmotic mechanism occurs during _________.

1 answer:

5 0

In photosynthetic cells, synthesis of ATP by the chemi-osmotic mechanism occurs during photosynthesis and respiration. Plants can only achieve photosynthesis during the day and then respire during the night because photosynthesis requires the sun's energy to perform the necessary reaction to produce oxygen.

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In chloroplasts, ATP is synthesized from ADP plus inorganic phosphate (Pi) in a reaction catalyzed by ATP synthase molecules tha

garik1379 [7]

Explanation:

Complete Question:

A. Blocking electron flow from one carrier to the next in the electron transport chains blocks formation of a proton gradient in the thylakoid.

B. Increasing the proton concentration difference across the thylakoid membrane is not associated with a parallel increase in the rate of ATP synthesis.

C. No ATP is synthesized when channel proteins that allow the free passage of protons are inserted into the thylakoid membrane.

D. No ATP is synthesized while the Calvin cycle is synthesizing carbohydrates and using ATP and NADPH at a high rate.

Correct: C. No ATP is synthesized when channel proteins that allow the free passage of protons are inserted into the thylakoid membrane.

Photophosphorylation describes a process in which the H+ made in previous steps of photosynthesis, and free electrons are used to obtain energy stored as ATP; in the electron transport chain move down the chain the energy they release is used in pumping protons out of the thykaloid space.

The high concentration of H+ from photolysis, outside the leads to increased H+ concentration within the thykaloid space, due to its high permeability. This forms a gradient where there is a differential in the number of protons on either side of the membrane the protons flow into the stroma through the enzyme ATP synthase, which makes the energy storage molecules of ATP from the reduction of ADP and inorganic phosphate, Pi. NAD+ functions as the terminal electron acceptor and is reduced to NADPH.

Thus:

a H+ concentration gradient is required for oxidative phosphorylation in the electron transport chain of the chloroplast, and thus the production of ATP
the H+ ion gradient must favor the flow of electrons into the stroma

The free flow of H+ disrupts the gradient, and H+ cannot flow into ATP synthase to produce ATP.

Further Explanation:

Photosynthesis is a chemical pathway that’s integral to producing energy in plants and other primary producers. Energy in the form of molecules of glucose is produced from light, water and carbon dioxide while oxygen is released. This occurs in several complex steps, photosynthesis is a rate limited reaction, depends on several factors including carbon dioxide concentration, ambient temperature and light intensity; the energy is retrieved from photons, I.e. particles of light, and water is used as a reducing agent. This occurs in the thykaloids, where pigment molecules like chlorophyll reside.

The chloroplast is a membrane bound organelle found in plants. It contains several invaginations of a plasma membrane called the thylakoid membrane. This contains chlorophyll pigments, in stacks called granum, while the internal spaces of the organelle are called the lumen. Liquid surrounds the granum, forming the stroma.

During the light reaction:

Light is absorbed by pigments in phosystem II (PSII). This energy is transferred among pigments til it gets to the reaction center, and is transferred to P680; this promotes an electron to a higher energy level where it then goes to an acceptor molecule.
Water supplies the chlorophyll in plant cell with replacement electrons for the ones removed from photosystem II. Additionally, water (H2O) split by light during photolysis into H+ and OH- acts as a source of oxygen along with functioning as a reducing agent.
the electron moves down an electron transport chain (to PS I)where it experiences continuous energy loss. This energy fuels the pumping of H+ from the stroma to thykaloid, leading to the formation of a gradient. The H+ move along their gradient and cross through ATP synthase, into the the stroma.
ATP synthase converts ADP and Pi to the energy storage molecule ATP.
The electron gets to photosystem I where it goes to pigments at P700. It absorbs light energy, the electron is promoted to a higher energy level, and passed to an electron acceptor. This leaves a space for another electron which is then replaced by one from photosystem II.
in the ETC, the molecule NADP is reduced to NADPH by providing H+ ions. NADP and NADPH are integral to the Calvin cycle where monosaccharides or sugars like glucose are produced after the modification of several molecules.

Learn more about photosynthesis at brainly.com/question/4216541

Learn more about cellular life at brainly.com/question/11259903

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6 0

2 years ago

A scientist performs an experiment to see if acids have an effect on the health of a particular type of plant. Three sets of pla

olga55 [171]

The question is not complete but it can be answered in general as the plants cannot survive in acidic conditions.

Answer: High acidity is harmful to this type of plant.

Explanation:

The plants that were kept in the higher acidic conditions are less likely to grow in higher acidic conditions.

The plants that were kept in more basic conditions will also not grow properly as the pH of the soil should be neutral, slightly acidic or slightly basic.

The plants that was kept as a control on the pH of 7 will grow the best as the pH is optimum for the growth of the plants.

The conclusion is high acidity is harmful for the life of the plants.

8 0

2 years ago

Why are Earth's materials and energy considered to be in equilibrium? (can be multiple answers)

butalik [34]

The correct answer is option A , C and D

The earths material is recycled and this can be visualized from the different chain cycles such as nitrogen cycle, carbon cycle , sulphur cycle, water cycle etc. These basic components which constitute all the matter existing on earth are continuously recycled and reused. Likewise the energy obtained from sun is neither created nor destroyed; it is only converted from one form of energy to the other form. Such as heat energy obtained from sun is converted into kinetic energy when it converts water into water vapor.

7 0

2 years ago

Read 2 more answers

Alleles A and a are located on a pair of metacentric chromosomes. Alleles B and b are located on a pair of acrocentric chromosom

Leto [7]

Answer:

See the second attached image showing the gametes from the parent with the location of the centromere indicating the type of chromosome

Explanation:

According to the position of the centromere, chromosomes can be of 4 types namely:

Metacentric
Acrocentric
Telocentric
Sub-metacentric

A metacentric chromosome is a chromosome that has no short or long arm. The arms are equal in length with the centromere joining the two sister chromatids located at the center.

Acrocentric chromosomes have unequal arm lengths with the centromere skewed towards one end of the chromosome.

Telocentric chromosomes have their centromeres at one end of the chromosome.

Sub-metacentric chromosomes have unequal arm lengths but the centromere is not as skewed to one end of the chromosome length as found in acrocentric chromosome.

The only possible gamete from aa bb parent is ab. Recall that the allele a is located on a metacentric chromosome while allele b is located on acrocentric chromosome.