What happens during G1 phase?

The layer cells that enclose the vascular tissue in the central region of the root is the?

V125BC [204]

Answer:

A) endodermis

Note:

The central cylinder is delimited by the endoderm, a layer of well-adjusted cells and endowed with special reinforcements on the walls, known as the Striae of Caspary.

3 0

3 years ago

What is the difference between extrinsic and intrinsic clotting?

KengaRu [80]

They're two different clotting pathways that use different factors. Though, the intrinsic and extrinsic pathways come together at factor X and eventually result in fibrinogen (factor I) being converted into a fibrin clot by prothrombin (factor II).

Extrinsic begins with factor VII and intrinsic begins with factor XII

8 0

3 years ago

How does treatment for a bacterial infection differ from treatment for a virus?

kari74 [83]

The answer is: you can treat bacterial infections, not viruses with antibiotics.

The use of antibiotics in viral infections is not effective and many organizations recommend the use of antibiotics only when there is a documented bacterial infection. The treatment of viral infections has been difficult for they are tiny and replicate inside the cell.

3 0

2 years ago

A host organism needs time, often days, to mount an immune response against a new antigen, but memory cells permit a rapid respo

nikklg [1K]

Answer:

The answer is D.

Explanation:

Viruses can evade the processing and presentation of antigens, for example by interfering with the expression of MHC class I proteins, although this increases their susceptibility to be detected by natural killer cells (NK). However, some members of the herpesvirus, papillomavirus, retrovirus, poxvirus and flavivirus families have also developed strategies to escape the attack of NK cells and promote their survival, inhibiting cell apoptosis. Finally, some pathogens often change surface antigens frequently, as in the case of influenza viruses (orthomyxovirus).

The human immunodeficiency virus (HIV) affects CD4 + T cells and degrades the host's ability to counterattack with a strong cell-mediated immune response. There are so many tactics of immune evasion used by HIV, which have so far hindered the development of an effective vaccine.

7 0

3 years ago

14). During the early 1700’s, a small group of pacifist Protestants fled Germany to avoid religious persecution. This group, the

abruzzese [7]

A) In the Dunker population, the frequency of IB allele is 0.3 and the frequency of i allele is 0.4. In the general population, the frequency of IB allele is 0.1 and the frequency of i allele is 0.5.

If:
$I^{A}$ - the frequency of IA allele
 $I^{B}$ - the frequency of IB allele
 $i$ - the frequency of i allele

Then:
 $I^{A} I^{A}$ + $I^{A} i$ - the frequency of individuals with A blood type
 $I^{B} I^{B}$ + $I^{B} i$ - the frequency of individuals with B blood type
 $ii$ - the frequency of individuals with O blood type

Let's first take a look on the Dunker population:
$I^{A} = 0.3$
$ii=0.16
$

Since there is only one possible genotype for O individuals - ii - the frequency of the allele i is square root of the frequency of O individuals:
 $i= \sqrt{ii}$
⇒ $i = \sqrt{0.16}$
⇒ $i=0.4$

Now, we have the frequencies of two alleles ( $I^{A}$ and $i$ ). To calculate the frequency of $I^{B}$ allele, we will use the formula:
 $I^{A} + I^{B} + i = 1$
⇒ $I^{B} = 1- I^{A} - i$
⇒ $I^{B} = 1-0.3-0.4$
⇒ $I^{B} = 0.3$

Now, in the general population:
$I^{A} = 0.4$
$ii=0.25$

Similarly to the work for the Dunker population:
 $i= \sqrt{ii}$
⇒ $i = \sqrt{0.25}$
⇒ $i=0.5$

$I^{A} + I^{B} + i = 1$
⇒ $I^{B} = 1- I^{A} - i$
⇒ $I^{B} = 1-0.4-0.5$
⇒ $I^{B} = 0.1$


b) A founder effect is a result of geographical separation of a few individuals from the original population. Those founding individuals will form a new population. The Dunker population was not only geographically separated, but also genetically. The group interbreeding was present resulting in increasing those allele frequencies that were the most common in the founding population. In this case, the most individuals from the founding population had B blood type.

6 0

3 years ago