why are Some substances allowed to cross the cell membrane while other substances are not?

Answers

Answer 1

Answer:

membranes are semipermeable so only let certain materials in and out; if there are carrier or channel proteins, then passive transport can occur otherwise active transport is required which requires energy.

Explanation:

membranes are semipermeable so only let certain materials in and out; if there are carrier or channel proteins, then passive transport can occur otherwise active transport is required which requires energy.


Related Questions

What do animals do with the carbon dioxide produced in their cells during cellular respiration?

Answers

Answer:

Explanation:

During cellular respiration animal cells combine oxygen with food molecules to release energy to live and function. Remember that cellular respiration produces carbon dioxide as a waste product. ... They release the carbon dioxide into the air as a waste product. Plants help animals and animals help plants.

The carbon dioxide produced in animal cells during cellular respiration is considered a waste and must be disposed of accordingly.

The carbon dioxide generated from cellular respiration in animal cells must be disposed off the cell because their build-up can be toxic to the cell.

Being a gas, carbon dioxide is got rid of by diffusing out of the cell while the oxygen required for cellular respiration usually diffuses in.

When carbon dioxide is allowed to accumulate in the cell, it might affect other processes such as the partial pressure of oxygen in the cell, and so on.

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A dolphin catches and eats small fish

Which type of organism in this scenario.

A. Consumer

B. decomposer

C. parasite

D. producer​

Answers

Answer:

A

Explanation:

The dolphin ate the fish. He 'consumed' something from the environment. However, this was not parasitic since the dolphin killed, not hurted the fish.

Answer: A don't be mad at meee if it's wrong, get mad at the person above me

Explanation:I'M TAKING THE EXAAAAM =(

A firefly uses chemicals in its body to produce a glowing body. What energy transfer is this?

Answers

Answer

Bioluminescence is a chemical reaction. It takes place inside the light-producing organ of a glowing creature. Fireflies, for example, make light in their abdomens. The chemical reaction produces energy in the form of photons.

Hope this helps! <3

I need Help please?????!!!

Answers

Force I believe because gravity only pulls

Answer:

force

Explanation:

Force is as follows, strength or energy as an attribute of physical action or movement.  (ex of physical action. push or pull)

Hope this Helps! :)

Have any questions? Ask below in the comments and I will try my best to answer.

-SGO

Which ecosystem is more stable - a potato field or a forest?

Answers

Answer:

A forest ecosystem is more stable than a potato field.

Explanation:

The forest ecosystem is a natural one and all the elements are balanced, they are managed by the nature itself.

The forest ecosystem is a natural one, and all the components are in harmony since nature herself manages the ecosystem.

Thus, A forest ecosystem, or simply a forest, is a community of plants, animals, microorganisms, and other species that interact with the chemical and physical elements of their environment.

The species in a forest ecosystem are depending on one another in order to survive, and they can be roughly categorized as producers, consumers, and decomposers based on their ecological roles.

The boreal forest that surrounds the Earth in northern latitudes is an example of a vast forest ecosystem. A forest ecosystem can also be as small as a microsite on a tree limb where mosses, insects, and microscopic species coexist.

Thus, The forest ecosystem is a natural one, and all the components are in harmony since nature herself manages the ecosystem.

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How does sugar affect people

Answers

Answer:

The effects of added sugar intake: higher blood pressure, inflammation, weight gain, diabetes, and fatty liver disease... are all linked to an increased risk for heart attack and stroke.

Explanation: Hope this helps <3

Crust is created at which type of plate boundary?

Answers

Answer:

At convergent boundaries

Explanation:

"continental crust is created and oceanic crust is destroyed as it subducts, melts, and becomes magma."

Hope this helps!!

Primer design is a critical step for the detection of a particular sequence in a sample. Which of the following would be true of primer design?

Answers

The group of choices is as follow:

A. RNA polymerase are added to the PCR mix to design random primers  

B. If detecting viral infection by PCR, the primers must not be complimentary (match) to regions of human DNA  

C. Pairs of primers must be designed, one to start amplification with Taq polymerase, the other to start amplification with human polymerase  

D. Primers are optional if you want to amplify all DNA within a sample

Answer:

The correct answer is - B. If detecting viral infection by PCR, the primers must be complementary to regions of human DNA.

Explanation:

Short, single-stranded segments of DNA sequences utilize in the real-time PCR or polymerase chain reaction technique are called primers. Primers used to hybridize the region of the segment needed to be amplified.

The human polymerase enzyme is not used in the PCR reaction and requires a 3'OH group to synthesize the DNA by amplification which is possible only in the presence of primers as they have a 3'OH.

Explain the steps (5) that would need to take place for primary succession to occur.

Answers

Answer:

The labels I-VII represent the different stages of primary succession. I-bare rocks, II-pioneers (mosses, lichen, algae, fungi), III-annual herbaceous plants, IV-perennial herbaceous plants and grasses, V-shrubs, VI-shade intolerant trees, VII-shade tolerant trees.

Explanation:

in any ecosystem, there are fewer carnivores than herbivores. why?​

Answers

Answer: There are more herbivores because all life depends on are primary producers

Ex; plants

Which polymer
can be found "freely floating" in the cytoplasm of a bacteria?
A) proteins
B) lipids
C) carbohydrates
D) nucleic acids

Answers

It’s actually bacterial DNA

Can someone help? I don’t understand this at all.

Answers

Answer: the part where it says *eyecolor* man/woman ect. you choose an abbreviation for it i’m think and then for #3 you would put cb or sum for color blind on the top left, the left side on that same square, ncb for noncolor blind on the bottom square on the left, and ncb above the top right place, fill in the area labeled cb/cb with cb cb, the area under would have cb ncb, top right would be ncb cb n the one under would be nbc nbc (a) 25% (b) 25%

Explanation:

.Explain why the scientific process is important when learning about diseases.

Answers

Answer:

The scientific process is important when learning about diseases because it allows to obtain reliable and valid knowledge about the different existing diseases, it helps in solving problems correctly and it is the best tool to nullify arbitrary opinions regarding a diagnosis or treatment, taking into account each of its stages.

Explanation:

The scientific method is a process through which relationships between facts are established to arrive at the verification of something. Through this step by step in which facts are discarded and added, the answers to findings are based. It is through the information generated by the research that it is possible to associate and / or integrate a set of symptoms and signs with a probable nosological diagnosis. Similarly, the selection of treatment and even the prognosis of patients depend on the information obtained from a population of subjects who share attributes; they depend, in a word, on research. Bearing in mind the scientific process, scientific thinking develops with practice, and for this it is necessary that there be constant reflection on the problems, have guides for the interpretation of medical reading, develop research protocols, learn to collect and analyze data about diseases.

Scientific is very important in order to obtain information about the disease.

The scientific process is important when learning about diseases because it provides information about various aspects of diseases as well as provides solution about cure of the disease.

This scientific process or method can be used for obtaining information about the causes of disease, its causing agents and cure for the disease so we can conclude that scientific is very important in order to obtain information about the disease.

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a neap tide has




A.) higher high tides and lower low tides than normal

B.) higher high tides and lower high tides than normal

C.) higher low tides and lower low tides than normal

D.) higher low tides and lower high Tides than normal​

Answers

Answer:

C

.....................

Which tool is used to test for nitrates?

A. turbidity test
B. pH meter
C. soil testing kit
D.water quality testing kit

Answers

The tool which is typically used for testing nitrates is: C. soil testing kit

Nitrogen is a chemical element with the symbol "N" and it has an atomic number (number of protons) of 7.

Basically, nitrogen is found in group (5) of the periodic table and as such it has 5 electrons in its outermost shell.

Oxygen is a chemical element with the symbol "O" and it has an atomic number (number of protons) of 8.

Generally, when nitrogen and oxygen react chemically, they produce a compound known as nitrogen dioxide.

In Chemistry, nitrates are chemical compound that comprises nitrogen and oxygen.

Also, nitrates are used in the production of soil fertilizers in agriculture.

In conclusion, a soil testing kit is mainly used to test the presence of nutrients such as nitrates in soils.

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What sort of farming defined the first type of agriculture?

Answers

Answer:

Agriculture and domestication probably started in the Fertile Crescent (the Nile Valley, The Levant and Mesopotamia). ... People probably started agriculture slowly by planting a few crops, but still gathered many foods from the wild. People may have started farming because the weather and soil began to change.

Explanation:

will the heat stored in the blood’s plasma be able to escape easily?

Answers

No because it cannot escape easily

Which statement describes a characteristic of the asthenosphere?
Temperatures are cool.
Consistency is solid.
Thickness is less than crust.
O Pressure is higher than crust.

Answers

Answer:

D

Explanation:

I am taking the test

The statement describes the property of the asthenosphere, which is that the pressure is higher than the earth's crust.

What are the properties of the asthenosphere?

The asthenosphere is the denser and weaker layer below the mantle of the lithosphere. It is approximately 100 kilometers (62 mi) and 10 kilometers (255 mi) below the Earth's surface.

The asthenosphere is the part of the upper mantle  below the lithosphere that participates in plate tectonic movement and isostatic regulation. It consists of peridotite, a rock that mainly contains the minerals olivine and pyroxene.

The asthenosphere is the mechanically weak and flexible region of the Earth's upper mantle. It is located under the lithosphere, approximately 80-200 kilometers below the earth's surface and extends to a depth of 700 kilometers.

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What is cancer? Explain what a doctor means when he or she says the cancer has “metastasized.” (Provide examples)

Answers

Answer:

A disease that causes cells to grow too rapidly

Explanation:

The cancer has spread to another part of the body where there originally wasn't any cancer. Ex: If someone was diagnosed with thyroid cancer and then later they're told the cancer has spread to their lungs

Cancer  is characterized by abnormal cell growth when a cell does not divide naturally, it is said to have metastasized, which means that the cancer has spread from one part of the body to another.

What is the significance of the cancer?

It is a type of condition where the person's normal cell growth is hampered, and it has a significant impact on an individual, leading to a wide range of symptoms such as pain and fatigue and increasing mental health issues and an example of metastasis is the brain cancer can move to the lungs and other parts. Due to the significant advancements in the diagnosis and treatment of cancer, an earlier stage can be detected and the later stage can be somewhat cured.

Hence, cancer is characterized by abnormal cell growth when a cell does not divide naturally, it is said to have metastasized, which means that the cancer has spread from one part of the body to another.

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What net force must act on the glass in order to make it accelerate to the right at a rate of 5 m/s^2 ? (Hint: Use F = ma.)


A. F = 10 N right
B. F = 2.5 N right
C. F = 5 N left
D. F = 0.5 N left​

Answers

Answer:

f = 2.5 N right

Explanation:

Answer:

Option B) F = 2.5 N right

What provides the energy to add the phosphate group back to ADP to form
ATP?
O oxygen we breathe
O excercise
O ATP in food we eat
O the food we eat

Answers

Answer:

D

Explanation:

I think that's the answer :)

The food we eat is correct

plz help i need this done fat thank you

Answers

Answer:

1,4,5

Explanation:

what is the structure of the cell wall

Answers

The cell wall is rigid and provides strength and protection. It is located outside of the cell (plasma) membrane. It is made up of different polysaccharides.

In modern taxonomy, species are the most
taxa.
broad
complex
specific

Answers

Answer:
Specific
Reason:
I got it right on a test

Species are the most specific in modern taxonomy.

Taxonomy is defined as the scientific method of classifying, identifying and naming living organisms.

In the hierarchy of living organisms, the largest group of organisms is the Kingdom. This is followed by:

Phylum

Class

Order

Family

Genus and

Species (which is lowest in hierarchy).

The species is the smallest unit of classification.

It is the most specific because the individuals within a species are:

Identical in appearance,Closely related and Can mate with one another to produce fertile offspring.

Therefore, species are the most specific in modern taxonomy.

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Discuss how constraints related to biology and management affect the choice of a crossbreeding system. Please be descriptive.

Answers

Answer:

Some important constraints:  

-Plant breeding: autogamy and allogamy, self-sterility, etc  

-Animal breeding:  trait compatibility

- Breeding systems in general (i.e., both in plants and animals): barriers for sexual reproduction  

Explanation:

Crossbreeding systems consist of the breeding between two breeds in order to develop progeny with particular advantageous phenotypic traits. In-plant crossbreeding systems, it is imperative to have into account whether the plant is autogamous (reproducing by self-pollination) or allogamous (reproducing by cross-fertilization), because it will affect the fitness of the progeny resulting from these breeds. Moreover, the biological mechanisms of self sterility and compatibility must be also taken into consideration. In-animal breeding systems, it is important to have into consideration that phenotypic traits we desire to obtain in the progeny must be compatible between races. In addition, the barriers for sexual reproduction are also an important issue both in plant and animal breeding systems, it thus being impossible, for example, to get a breeding between Chihuahua and Great Dane dogs.

Who is Thomas Malthus?

Answers

Answer:

Thomas is an English economist and demographer. He is best known for his theory that population growth will always tend to outrun the food supply and that betterment of humankind is impossible without stern limits on reproduction.

Explanation:

5. Animals depend on plants for carbon dioxide..... True or False ​

Answers

true they depend on plants forco2

Answer:

No

Explanation:

Animals get Carbon dioxide from the air, and carbon dioxide is emitted by burning of fossil fuel

The vertebrate lung first appeared in ___________.

Answers

Answer:

fishes

Explanation:

A progenitor feature found in early boney fish served as the basis for the development of the vertebrate lung.

What are vertebrate lungs?

The lung of modern vertebrates evolved from a structure that was present in the ancestors of early boney fish.

Lungs in vertebrates originated as extra air-breathing organs in primordial fishes and were ventilated by buccal pumping when they first appeared. In more modern fishes, the organ formerly known as the lungs has been replaced with the hydrostatic swimbladder. This fundamental kind of unicameral lungs and the buccal pumping ventilation observed in these lungs can also be found in more modern amphibians.

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help me with the one that is in blue

Answers

Answer:

I think one is nitrogen. We have approximatly 78% of that in the atmosphere.

Another would be oxygen we have 21% of that.

We have argon and we have 0.93% of that.

Lastly we have carbon dioxide. And we have 0.04% of that.

Hope this helps.

use your own words to explain planetary gravitation. provide an example.

Answers

The planets moons movements and the attraction that can be caused between it

Example : Pluto gains a fourth moon Or a massive new planet in our solar system
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