how many chromosomes are there in human ovum​

Answer:

Humans are not that different from other animals, but vary in the finer detail.

Indeed most amniotes (terrestrial organisms with fetuses surrounded by membrane) work pretty well along the same principles, and there’s also much in common as far back as you want to go, really, on land or in water.

And my next semi-random thought is to say that cellular differentiation, like real estate (apparently), is all about location, location, location. Where the cells are, or where they came from, seems to matter a lot.

Actually, it’s more about layers. Like an onion. Or a cake. (I can’t believe I’m writing this, and apologies to any Shrek fans out there.)

What I mean to say is that some understanding of developmental embryology will help here. To simplify things enormously, our adult cell types ultimately arise from embryonic stem cells. These stem cells are multi-purpose and programmable, or pluripotent in a sense, and capable of making whatever type or form of cell is requested. They just need to be “told” what to do. And just tiny bits of code do exactly that, flipping switches on or off as required, based on cues like orientation, chemical gradients, and proximity.

Now a quick read of the links above will explain it all, but I’ll press on anyway. Out of that initial programming arises our ‘germ layers’, the mesoderm, the ectoderm and the endoderm. We are, after all, triploblastic. 3 layers, get it?

But you knew that.

In case you didn’t, these layers in effect give you a scaffold or more accurately perhaps a tube comprising an inside, outside, and a middle. Where your cells are hanging out in that tube matters, in that they pick up on their location and auto-magically become functionally relevant to that space. In a sense, I mean. Refer back to location, location, location.

Just knowing that pattern of proximity, gradients, and orientation more than simply sets the scene. Whether you work forwards or backwards from there, you will hopefully see that these “germ layers” derive quite simply from a much earlier differentiation, and then complexify. In that sense you have your answer - a complex set of diverse cell types arises by differentiation from an earlier, simpler differentiation. Which sounds a bit clunky when I write it out, but it gives a general idea.

So how does this complicated process happen?

Well, as I mentioned chemical gradients are probably to blame here. And it actually starts before fertilisation, in that the egg itself is already semi-structured and bathed in chemicals with a high-low gradient of some sort. In that sense it’s giving cellular differentiation a head start (there’s a pun there), by setting up some sort of polarity from the beginning. At the very least we get some ends happening, or a top and a bottom if you like.

Now, again simplifying things enormously, your average fertilised egg, or zygote, has by definition a complete set of your DNA ready and waiting, which contains the code for every protein-making gene, plus transcription factors, plus whatever else gets copied for various reasons, including those we haven’t teased out as yet.

Note that those transcription factors really matter. We may have around 20,000 protein-expressing genes, but we also have some 1,500 transcription factors that seem to switch the genes on, off, or arguably and effectively somewhere in between. Well, they work in combination and by that we get a huge amount of variation in expression, and thus our cellular diversity as well.

And all of that DNA goodness is sitting in that zygote, bathed in chemicals that may vary very slightly from top to bottom and side to side as it were, by concentration and by other traits, like temperature. Several such things interact, including orientation and proximity to neighbours, but let’s assert (based on experiments) that the gradient is important, and that it continues to guide the “differentiation” process as new cells are born.

Which is to say that by this process of reading the DNA and expressing only the genes that are switched on by the helpful and gradient-sensitive (say) transcription factors, we get set up to form those 3-D axes and the scaffolding that will guide our cellular replication strategy. Which then produces a result that with each round of replication becomes subtly different and more diverse. Over time the subtlety gives way to more recognisable layers and specialisation in function.

Perhaps not the neatest, clearest explanation but the quickest and least baffling one I can come up with right now. As always, read the links to get a better grasp.

Answer:

During the development of an organism, cells differentiate into many distinct cell types. How does a single fertilized egg cell develop into so many different types of specialized cells? ... They both cannot produce all cells. Multipotent- limited to replacing cells in the tissue where they are found.

Answer:

i think its A. burning coal in a power plant

Explanation:

sorry if im wrong but please let me know if this is correct or not

The method of generating electricity that does not use alternative energy resources is burning coal in a power plant.

Alternative energy resources are eco-friendly resources that can be used to produce energy.

These are renewable resources and can not be extinct.

These resources do not pollute the earth.

Examples are windmills, solar panels, hydropower, etc.

Thus, the correct option is a. Burn coal in a power plant.

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Answer:

A

Explanation:

When the population is well below the carrying capacity, it results into Logistic Growth.

As competition increases and resources become increasingly scarce, populations reach their carrying capacity causing growth rate to slow nearly to zero.

This produces an S-shaped curve of population growth known as the Logistic Curve.

Resources important for the survival of the species can act as a factor for Carrying Capacity .Example- For plants , it is water, sunlight, nutrients and space and for Animals- Food, Water, Shelter and Nesting Space.

Limited quantities of these resources results in competition between members of the same population or Intraspecific competition.

Examples of Logistic Growth are:

Yeast - A microscopic fungus can produce S shaped curve when grown in test tube.

Logistic Growth takes place when population's per capita growth rate decreases as population size approaches a maximum imposed by limited resources i.e. the carrying capacity.

Ecologists uses different methodologies for modelling Population Dynamics, amongst which major ones are Exponential Growth and Logistic Growth.

When the per capita rate of increase takes the same positive value regardless of the population size, it results into Exponential Growth whereas the per capita rate of increase decreases as the population increases towards a maximum limit, then we get Logistic Growth.

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Answer:

Explanation: 1. Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles.

2.  Organic, Clastic and Chemical Sedimentary Rocks.

3. The formation of coal takes millions of years, which is why it is an exhaustible and non-renewable natural resource.

It was formed around 300 million years ago when the earth was covered with swampy forests.

When plants in these forests- mainly trees, mosses, ferns, and reeds died, they fell into the swamps.

Thus there was a thick layer of dead vegetation in the swamp formed.

4. Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering.

6.Squeezed and compressed over time, the sediments become 'consolidated' (made solid) into layers of rock. Stratigraphy is the study of those layers Cementation occurs when dissolved mineral components deposit in the interstices of sediments. It is the sticking together of sediment that forms a rock.

7. It is used by marine biota to form a shell frame. Shells of marine animals are rich in carbonate minerals. When the marine animals die, the shells will accumulate and settle in a place so that rocks are formed.

8. This may be due to the overburden load, which is essentially the weight of all the material above the layer of minerals in question squashing them flat. Or it may be due to deformation caused by the movements of tectonic plates which often causes a form of deformation known as shearing where two things slide past each other. When this occurs in ductile rock masses, it acts to flatten and rotate mineral grains so that their long axis is parallel to the shear plane.

Answer:

c.16J

Explanation:

because kinetic energy =1/2mv²

1/2 ×2×4²=16J

Answer:

Ear canal

Explanation:

Answer:

b. The DNA fragments move towards cathode under electric field through the matrix.

Explanation:

Gel electrophoresis is a molecular biology technique used to separate DNA fragments based on size using electric current. The electric current passes through a GEL (agarose gel is commonly used) matrix. Due to the fact that DNA is negatively charged, they tend to move towards a positively charged electrode called ANODE.

However, the smaller the size of the DNA fragment, the faster and farther it moves along the matrix. Gel electrophoresis is indeed a technique used to check how progressive a restriction enzyme has been able to digest DNA molecule into fragments.

Answer:

What language is this?...

Answer:

There are four major classes of biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids), and each is an important component of the cell and performs a wide array of functions.

Four main categories of organic macromolecules are as follow:

Macromolecules are polymers containing long chains of molecular sub-units known as monomers. These play an important role in biophysical processes and composed of thousands of atoms that are covalently bonded.

Carbohydrate is a biomolecule having carbon, hydrogen and oxygen atom.It is the main source of energy of the body.

Lipids are macromolecules that are insoluble in water and the main function is to serve as structural component of cell membrane.

Proteins are macromolecules that are extremely complex in structure and made up of amino acid residues joined by peptide bonds.

Nucleic acids are biopolymer macromolecules and composed of nucleotide. The function is to carry genetic information which helps to make RNA.

Therefore,Four main categories of organic macromolecules are as follow:

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Answer:

think it's A but not sure

all of the above  cause the cardiovacular system help you move your blood

Answer:

1. all above

2. valves

3. arteries

4. gorta

5. muscle

Explanation:

Answer:

Insiso "d"... The ovary phase depends on the days after emnarazo.

Answer:

D ovulation phase.

Explanation:

Answer:

Relative Dating of rock layer

Answer:

option C is correct answer of this question

hope it helps

it is balanced equation

The example of a balanced chemical equation is 2H₂ + O₂ → 2H₂O. Thus, the correct option is C.

A chemical equation is the symbolic representation of the chemical reaction in the form of symbols and chemical formulas such as H₂O. Chemical equation are generally are unbalanced however, these reactions can be balanced.

Balancing a chemical equation refers to balancing the stoichiometric coefficients on both the reactants and products side of the reaction which is because the chemical equation must obey the law of conservation of mass of the atoms.

2H₂ + O₂ → 2H₂O

This reaction has 4 H and 2 O atoms.

Therefore, the correct option is C.

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Answer:

The fiberglass is the most affective at keeping the ice cream from melting.

Explanation:

The bolder dots are the fiber glass, and the line is not going up (melting), so it's the least melted.

Answer:

By a mutation that altered the shape of their wings, making them incapable of producing the chirping noise. The feat was achieved over less than 20 generations, a mere evolutionary blink of an eye, and, with the crickets living just a few weeks, a very rapid process.

Explanation:

Answer:

The change seems to have been caused by a mutation that altered the shape of their wings.

Explanation:

Makes them incapable of producing the chirping noise. The feat was achieved over less than 20 generations, a mere evolutionary blink of an eye, and, with the crickets living just a few weeks, a very rapid process.

Answer:

Our of the cell

Explanation:

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The part of the plant that takes in carbon dioxide from the air for photosynthesis stomata.

Answer:

A

Explanation:

Answer

hi, your answer is steel

Explanation:

because a skyscraper wouldn't stand well in bad weather as cardboard everything would eventually get wet. it couldn't be rubber, bc rubber would make it fall down a little. Plastic is strong, but eventually it wears away. so, steel is your answer

Answer:

He should request type O on his dating survey.

Opine's blood type must be AO to have a higher probability of producing O offsprings.

Explanation:

O blood type is recessive so, when it is paired with another blood type like B or A, these would be dominant, giving B and A blood, respectively.

O blood type results are possible thanks to OO genotypes.

If the man's blood type is A, to have a higher chance of producing OO offsprings, his blood should be AO. The other possibility is that he has AA blood, which will result in a low probability of OO offsprings.

As regards the mother, her blood type should be OO.

We can see this more clearly in Punnet Square.

║ A ║O

O║AO║OO

O║AO║OO  

There is a 50% of probability of having O offsprings with AO and OO.

  ║ A ║A

O║AO║AO

O║AO║AO

With AA and OO, the probability is 0%

 ║ A ║O

A║AA║AO

O║AO║OO

With both parents having AO, blood the probability of having a OO offspring is 25%.

In conclusion, the higher chances of producing a OO offspring is if the parents are AO and OO.

Answer:

it's C. They attract pollinators

Answer:False

Explanation:Mitosis

Answer:

The heat generated by the magma chamber has changed these sedimentary rocks into the metamorphic rocks marble, quartzite, an hornfels. Regional Metamorphism occurs over a much larger area. This metamorphism produces rocks such as gneiss and schist. ... They are generally as hard and sometimes harder than igneous rocks.

If sedimentary rock, pressed inside the crust and treated with a high pressure and temperature, then it can change over time into a hard metamorphic rock.

A sedimentary rock is mad up by the decomposition of minerals and other organic matter near the water surface.

These rocks are soft, such as limestone.

These rocks can turn into hard metamorphic rocks if they came in contact with high pressure and temperature.

Thus, by high pressure and temperature, the sedimentary rock change into hard metamorphic rock.

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Explanation:

D

Use the chart. The first amino acid is AUG

AUG is found in the row A, column U, and AUG is the 4th letter in the box, the sequence for it is met.

Looking at the next 3, UGG

The code for that is trap sk it has to be d.