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2 years ago

Explain why the cell membrane is described as selectively permeable

1 answer:

8 0

Hello,
The Cell Membrane is described as selectively permeable because it allows only certain molecules or ions to pass through the membrane by active transport or passive transport.

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Does sugar molecules provide all elements needed to make four types of macromolecules?

fomenos

Answer:

No, If that was the case, then we should only be eating carbohydrates.

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2 years ago

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A student observed several cell layers positioned on top of one another in the high power field of view I compound light microsc

shepuryov [24]

the student should scrap off the layers until a very thin layer remains and put it back on the microscope then the student will be able to view the details of only one cell layer

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1 year ago

A vehicle's headlights should be utilized ______ to ensure the safety of the driver and of others.

gregori [183]

The answer to this question is E. all of the above.

In all of these situations, it is necessary for you to use your headlights to ensure your safety and your ability to see the road in front of you.

Hope this helps!

4 0

1 year ago

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If 32 packed volume units of cells are separated from 46 volume units of plasma from a blood sample, the haematocrit is _______

nordsb [41]

Answer:

If 32 packed volume units of cells are separated from 46 volume units of plasma from a blood sample, the hematocrit is 41,02% percent. The hematocrit value is within the normal range.

Explanation:

Hello!

Hematocrit (or packed cell volume -PCV-)is defined as the percentage of red blood cells (vol%) in a blood sample. One common method of determining it is by centrifuging a heparinized blood sample in a capillary tube at 10 000 RPM for five minutes. This separates the blood sample in two layers, formed elements (RBC and WBC) and Plasma.

The length of the layers is directly measured from the tube and represents the volume of packed cells and plasma. Since the number of white cells is negligible compared to the number of red cells, the formed elements are considered to represent the red blood cells.

The hematocrit can be calculated as the volume of packed cells divided by the total volume of the blood sample.

$\frac{PCV}{TOTAL(pcv+plasma} * 100$

In the question:

$\frac{32}{32+46} * 100$ = $\frac{32}{78} * 100$ = 41,02%

In humans the normal hematocrit range is 40,7% to 50,3% for men and 36,1% to 44,3%. Taking these reference values into consideration, this sample is within the normal range.

I hope you have a SUPER day!

4 0

2 years ago

Last week you were wondering what Jessica and Tom's babies might look like with respect to their eyebrows and earlobes (both Tom

mash [69]

Answer:

25%

Explanation:

The possible genotypes and phenotypes are:

EE or Ee: thick eyebrows
ee: thin eyebrows
FF or Ff: free earlobes
ff: attached earlobes

Tom and Jessica have thick eyebrows and free earlobes. Tom's mother has attached earlobes, so Tom must have inherited an f allele from her, and because he has free earlobes he must be heterozygous Ff. We assume Jessica is homozygous for free earlobes FF.

Tom's mother and Jessica's father have thin eyebrows, so they are both ee and therefore both Tom and Jessica must be heterozygous Ee.

From the above information, Tom has the genotype EeFf and Jessica is EeFF. If you do a Punnett Square of this cross, you'll get that the probability of having a child with free earlobes and thin eyebrows (eeF_) is 25%.

6 0

1 year ago