Someone help please 20 points

Answer:

Found in plant cell walls

Chitin is all of the following except it is found in the plant cell wall. So, the correct option is D.

It is the outermost layer of a cell that can be tough, flexible, and sometimes rigid. Its function is to provide structural support and protection to the complete cell.

The Cell-wall of fungi is made up of chitin. It is composed of N-acetylglucosamine subunits. It is also composed of linear fibrils like cellulose. Mostly, found in insect and crustacean shells.

Therefore, Chitin is all of the following except it is found in the plant cell wall.

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Answer:

Theory of Measurements:

Leaf photosynthetic rate is measured by enclosing a leaf in a closed, transparent chamber and measuring the decrease in carbon dioxide concentration as a function of time.

Rocks from the Ordovician Period contain evidence that plants began colonizing dry land at this time. Most experts agree that the ancestors of land plants first evolved in a marine environment, then moved into a freshwater environment and finally onto land.

Ordovician Period, in geologic time, the second period of the Paleozoic Era. It began 485.4 million years ago, following the Cambrian Period, and ended 443.8 million years ago, when the Silurian Period began. Ordovician rocks have the distinction of occurring at the highest elevation on Earth—the top of Mount Everest.

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Answer:

Hopefully this is correct!! Not sure...

Explanation:

4) D

5) A

6) C

Answer:

You can't see the blood vessels themselves because vision depends on a process that makes it impossible to see things that are stationary with respect to the retina. Light receptors in the retina respond only to changes in light reaching them, not to a steady image.

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If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will complete the cell cycle and divide normally.

The cell cycle may be defined as the entire sequence of events happening from the end of one nuclear division to the beginning of the next nuclear division.

There are three major checkpoints in the cell cycle. One at the end of the G1 phase, the second at the end of the G2 phase, and while third is during the M phase.

Therefore, if mammalian cells receive a go-ahead signal at the G1 checkpoint, they will complete the cell cycle and divide normally.

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Answer:

8 Newton net force

Explanation:

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Replication occurs in three major steps: the opening of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment.

The three steps that are required for DNA  replication are initiation, elongation and termination.

The process in which DNA of a cell under go duplication to produce two copies during S-phase of cell cycle called as DNA replication.

It involves 3 steps such as initiation step where the origin of replication of DNA molecule undergo unwinding into two DNA strands.

An incomplete unzipping by forming replication fork is created is catalyzed by the helicase enzyme.

Secondly in elongation step the DNA polymerase enzymes make the complementary sequence against each parent template strand.  

It is an unidirectional, one strand which is synthesized in a continuous manner called leading strand, the strand which is synthesized in a discontinuous manner called lagging strand with Okazaki fragments.

Termination occurs in the last step, when the parent molecule has been completely replicated.

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Crabs, pilchards, blennies and snappers are the examples of secondary consumers.

Crabs, pilchards, blennies and snappers are considered as secondary consumers because they feed on primary consumer which feed on producers such as plants and algae. Secondary consumer are those organisms which feed on herbivorous organisms or primary consumers.

They can feed on producers due to different digestive system so we can conclude that crabs, pilchards, blennies and snappers are the examples of secondary consumers.

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Answer:

cell nucleus

In eukaryotic cells, most DNA is located in the cell nucleus (though some DNA is also contained in other organelles, such as in the mitochondria and the chloroplast in plants). Nuclear DNA is organized into linear molecules called chromosomes.

Explanation:

Mendel concluded that the alternative forms of each trait are coded by discrete factors, which were called alleles that combine in pairs to express the trait. Traits are inherited in discrete units and are not the result of "blending."

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After making many crosses that involved different traits -such as plant height, or flower colors-, Mendel observed that, per trait, the F1 only expressed one of the alternative forms, while de other one disappeared.

Mendel named dominant the expressed variant.

Mendel then let these new plants auto pollinate and observed the results in the second generation, F2.

He saw that the variants that had previously disappeared among the F1, reappeared again. Both alternatives for each trait were present in the F2.

Mendel named recessive the second alternative variant.

Mendel explained his results by arguing that discrete factors were responsible for these phenotypes.

Mendel conclusion about his experiments was that per trait -flower color of plant length-, each plant had a pair of factors -which he named alleles-, and that each factor coded for one of the alternative forms of the traits -white or purple, tall or short-.

He thought that alleles separate -segregate- during the process of gamete formation.

The First Mendel's Law is the first conclusion he took about his experiments and is known as the segregation principle.

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The key that allows a cell to progress beyond the restriction point is the phosphorylation of specific proteins (for example RB) by Cdk. The cyclin-dependent kinases (CDKs) are able to phosphorylate different substrates.

Cyclins regulate the progression of the cell cycle by their interaction with cyclin-dependent kinases (Cdks).

This binding activates the Cdks, thereby converting them into functional enzymes that phosphorylate target proteins and thus regulate cell cycle progression by bypassing restriction points of the cell cycle.

CDKs can phosphorylate different substrates by transferring phosphate groups from adenosine triphosphate (ATP) to specific amino acidic residues in these substrates.

For example, CDKs phosphorylate Rb proteins and thus regulate their activity during the cell cycle.

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Answer:

Its B I took the test

Explanation:

Answer:

sodium and bromine

Explanation:

The one valence electron from sodium would be transferred to the bromine atom so they can both have an octet.

Which two atoms form an ionic bond?

Answer : A

Explanation : Ionic bond is a type of chemical bond and binds the chemical molecules together. Ionic bond is formed by the transfer of electrons from an electropositive element ( metal) to the electronegative element (non metal).

Sodium is an electropositive element and contains one positive charge. Bromine is an electronegative element with a single negative charge over it. Sodium gives the electron to bromine and results in the formation of ionic bond.

Thus, the correct answer is option (C).

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Indicator organisms are organisms that are utilized to detect the presence of another organisms that cannot be easily identified.

We do not test for pathogens like salmonella directly but use an indicator organism like coliform because these pathogens are not easily isolated and they are much harder to identify.

Pathogens like salmonella are not tested for directly because they are much lower in numbers when found in wastes or waterbodies and to identify them directly is expensive.

Also testing directly for these micro-organisms is very expensive and non-viable. So it is better to use indicator organisms to detect their presence.

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Given what we know about the biology of the small intestine, we can confirm that the macromolecules are being absorbed into the "Epithelial cells".

The small intestine is in charge of absorbing the nutrients, which we require in order to survive and perform even the most basic metabolic processes, from the food that we ingest. In order to be able to perform this function, the cells in question have specialized epithelium which consists of Microvilli.

Microvilli can be thought of as membrane protrusions that serve to expand the surface area of the epithelial cells. This allows the cells to have a greater area through which to absorb nutrients such as the macromolecules mentioned.

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Answer:

Remember that glycolysis produces two pyruvic acid molecules per glucose molecule along with two of the hydrogen-carrying NADH molecules. Remember also that the Krebs cycle produces NADH as well as another hydrogen carrier called FADH2.

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Objects are brought into focus on the retina by changes in the curvature and thickness of the lens.

The lens basically directs light rays onto the retina. The lens is clear and replaceable if necessary. As we age, our lenses deteriorate, necessitating the use of reading glasses.

The lens is normally clear and is located behind the iris. The pupil directs light to the lens.

Small muscles attached to the lens can cause the lens to change shape, allowing the eyes to focus on objects that are close or far away.

Light bends (refracts) and focuses on the retina at the back of the eye as it passes through the lens.

The lens's thickness and curvature can be adjusted to focus on objects at various distances and ensure that the image is as clear as possible (this process is known as accommodation).

Thus, eye lens helps to focus the object.

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Answer:

the answer is c

Explanation:

filtration

Answer:

b. Pepsin and trysin

Explanation: is correct

Answer:

Summary. Through the process of cellular respiration, the energy in food is converted into energy that can be used by the body's cells. During cellular respiration, glucose and oxygen are converted into carbon dioxide and water, and the energy is transferred to ATP.

Answer:

smog

Explanation:

Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities.

Answer:

Sedimentary.

Explanation:

Sedimentary will determine if water temperature affects the weathering of sedimentary rocks.

Answer: Independent Variable

Explanation: Already explained this one in another post.

A positive feedback loop that affects climate is change as the number of plants increases, the amount of CO2 decreases.

Scientists agree that one of the most effective ways to absorb part of the CO2 from the atmosphere would be to plant more trees, as they use CO2 to grow and release oxygen, this action brings benefits to the entire environment.

With this information, we can conclude that A positive feedback loop that affects climate is change as the number of plants increases, the amount of CO2 decreases.

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Answer:

d. All of the above

Explanation: correct

Answer:

? why did you post this

Explanation:

Answer:

To spread carbon dioxide and oxygen.

Explanation:

Plants produce carbon dioxide and oxygen. This is called photosynthesis.