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2 years ago

What unexpected observation helped lead darwin to develop the theory of natural selection

Biology

2 answers:

algol [13]2 years ago

7 0

100% thank you so so so much

slava [35]2 years ago

5 0

Darwin’s most important observations were made on the Galapagos Islands. This is a group of 16 small volcanic islands situated off the west coast of Ecuador, South America.

Darwin observed that organisms on the Galapagos were similar to, yet different from, one another and from similar species in South America. For example, the giant tortoises on one island had saddle-shaped shells, while those on another island had dome-shaped shells. People who lived on the islands could even tell the island a turtle came from by its shell. This started Darwin thinking about the origin of species. He wondered how each island came to have its own type of tortoise.

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When a group of young geese watch the first thing they see after being born in order to learn behaviors, they are _______.

pshichka [43]

Answer: Imprinting

Explanation: A group of young geese watch their parents moving and they start moving as like of their parents because after they are born the first character which they see is known as Imprinting.

This is a phychological and phase sensitive learning. This patterns occurs at a particular age. This pattern is used to describe the situations in which the person or animal learns from the stimulus of the environment.

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2 years ago

During the transmission of signals across a neuromuscular junction, which of the following happens first?

Gre4nikov [31]

Answer:

The correct answer is A acetylcholine binds to a receptor protein on the motor end plate

Explanation:

The neurotransmitter acetylcholine is released by the motor neuron during the transmission of signals across a neuromuscular junction.

The released acetylcholine then diffuses the synaptic cleft and binds to the receptor protein present on the membrane of muscle fibre.

This ultimately result in the influx of sodium ion inside the muscle cell thereby causing depolarization to generate an action potential.

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2 years ago

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Explain how consuming an acid neutralizing antacid might affect protein digestion. Apply the concept of activation energy to sup

Deffense [45]

In the stomach, the enzyme pepsin has the function to break proteins into smaller units-polypeptides. Pepsin is synthesized and secreted in an inactive form- pepsinogen. Activation energy (the minimum amount of energy that is required to activate an enzyme) is achieved in the acidic medium (pH from 1 to 3). So, the activation of pepsin (conversion of pepsinogen to pepsin) is possible thanks to the cells in the stomach lining which produce hydrochloric acid (HCl), causing the stomach contents to have a low pH.

Antacids neutralize the acid made by the stomach, affecting the digestion.

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2 years ago

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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

Arsenate is a toxic ion that can interfere with both glycolysis and oxidative phosphorylation. Arsenate resembles inorganic phos

svetoff [14.1K]

Answer:

In the presence of arsenate glycolysis produces fewer ATP and NADH molecules per glucose molecule.

Explanation:

it is supposed to be 2 molecules of 3-phosphoglecerate with each producing 2 ATP making a total of 4 ATP gain but since it is just one and arsenate, only 2 ATP will be generated instead of four, thus ATP yield is reduced.

3 0

2 years ago