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3 years ago

Define the term active transport in terms of concentration gradient

2 answers:

4 0

Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration—in the direction against some gradient or other obstructing factor (often a concentration gradient).

elena55 [62]3 years ago

3 0

<h2>answer:</h2>

Active transport is the movement of molecules from a region of their lower concentration to a region of their higher concentration

<h2>explanation:</h2>

Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration—in the way opposite to some gradient or other obstructing factors (often an intensity gradient).

While active transport, particles travel against the concentration gradient - and hence need an input of energy from the cell.

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Which statement about natural selection is true?

STatiana [176]

Answer: c.Natural selection is the process by which organisms with more beneficial traits are more likely to survive and reproduce.

Natural selection is the differential survival and reproduction of individuals because of differences in the phenotype. Phenotypic characteristics favors the survival of some organisms in the population better than others. Example given by Darwin population of colored beetles green and red belonging to same species. Green ones mimic the color of grass not noticed by birds but red ones were noticed and eaten by birds. This is the selection by nature for better suited individuals. Green color gave the survival advantage to these beetles which is a phenotypic characteristic therefore, they will produce more offsprings than the red ones and also pass on the phenotypic trait to their offsprings.

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3 years ago

Read 2 more answers

Give an example ecological disturbance. Light Disturbance? Extreme Disturbance.

nalin [4]

Answer:

In contrast, major disturbances include large-scale wind events (such as tropical cyclones), volcanic eruptions, tsunamis, intense forest fires, epidemics, ocean temperature changes stemming from El Niño events or other climate phenomena, and pollution and land-use conversion caused by humans.

Explanation:

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2 years ago

What happens during the initiation step of DNA transcription? A ribosome attaches to the initiation codon of a completed mRNA st

Amanda [17]

Answer:

A portion of the DNA unwinds and RNA polymerase attaches to the DNA within the transcription bubble.

Explanation:

Transcription is the process in which DNA template is used to synthesize mRNA.

There are three steps of transcription:

Initiation

It is the process in which a portion of DNA unwinds and RNA polymerase binds to the promotor region on the DNA.

Elongation

It is the process in which RNA polymerase moves along the DNA template and synthesizes mRNA. During this process, unwinding of double stranded DNA takes place.

Termination

As the RNA polymerase moves along the DNA template, it finally reaches a termination signal and then stops synthesizing. It is followed by the detachment of the newly formed mRNA and RNA polymerase from the DNA.

QUESTION:

A ribosome attaches to the initiation codon of a completed mRNA strand.

This is the incorrect answer choice as this process does not happen in the process of transcription. This event happens in the process of translation in which mRNA is used to synthesize proteins or amino acids. mRNA attaches to ribosome during this process.

RNA polymerase moves along the template strand of the DNA creating an mRNA strand.

This is the incorrect answer choice as this event takes place in the process of elongation.

A portion of the DNA unwinds and RNA polymerase attaches to the DNA within the transcription bubble.

This is the correct answer choice as this event takes place in the process of initiation of transcription

The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand.

This is the incorrect answer choice. This event takes place in the event of termination of transcription.

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3 years ago

Aquaporins are proteins that control the passage of water molecules across a cell membrane. The protein forms a pore, or opening

timofeeve [1]

The two different molecules of aquaporin will have different sequences of amino acids

Explanation:

Aquaporins are an integral type of membrane proteins. They act as water channels and their function is to transport water and other solute materials across cells membranes and thereby control and regulate the water content of the cells.

They are formed by clustering of four water channel monomers forming a tetramer.

Each aquaporin is made up of a specific linear sequence of amino acids and variations in the sequence leads to formation of different aquaporins.

There are more than 10 types of aquaporins are known. The sizes of the aquaporins differ according to their pore diameter of each type and this difference leads to the selective permeability of water across cell membranes.

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3 years ago

Explain how a change in thermal energy causes matter to change from one state to another. Give two examples

Bingel [31]

Thermal energy causes matter to change state beacuse evrything has heat which is thermal energy hore heat is more thermal energy.
Ex.Ice changes into water
Ex.Water changes into water vapor

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3 years ago