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krok68 [10]
2 years ago
15

Which of these statements about trophoblast is false?

Biology
1 answer:
lukranit [14]2 years ago
7 0

Answer:

The statement C that says ''is derived from the inner cell mass'' is false.

Explanation:

The trophoblast is a structure composed of a set of cells (cytotrophoblast and syncytiotrophoblast), which are shaping the outer layer surrounding a blastocyst, during the earliest stages of embryonic development that mammals pass.

The trophoblast provides nutritive molecules to the developing embryo and facilitates its implantation to the uterine wall due to its ability to erode the tissues of the uterus, that is, it is responsible for making it possible for the embryo to be implanted in the uterine endometrium. Thus, the blast can join the cavity formed by the uterine wall, where it will absorb nutrients from the fluid from the mother.

During the third week, embryonic development includes the development of the trophoblast. At the beginning, the primary villi are formed by the internal cytotrophoblast which is surrounded by the outer layer of syncytiotrophoblast. Then, the cells found in the embryonic mesoderm are directed to the primary villous in the third week of gestation and when it ends, the mesodermal cells begin to be singled out to form blood vessel cells.

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In Drosophila, vestigial (partially formed) wings (vg) are recessive to normal long wings (vg+) and the gene for this trait is a
Marina CMI [18]

Answer/ Explanation:

a. The genotype of a homozygous white eyed long winged female would be Vg+Vg+XrXr. We denote the white allele as recessive (r) because the XY male only has one copy and yet has red eyes, so the red eye trait (R) must be dominant. A homozygous red eyed vestigial winged male would have be VgVgXRY. The possible gametes for the female are Vg+Xr only. For the male, the possible gametes are VgXR or VgY

The attached punnett square shows the results of the cross. The females will all be Vg+VgXRXr. The males will all be Vg+VgXRY (must inherit Y from father). That means they will all  have normal length wings, the males will have white eyes and the females will have red eyes.

b. The F2 flies arise from intercrossing the F1, so the cross will be Vg+VgXRXr x Vg+VgXRY. The possible gametes for the mother are: Vg+XR, Vg+Xr, VgXR or VgXr. The possible gametes for the father are Vg+Xr

, Vg+Y

, VgXr

, VgY

. The attached punnet square shows this cross. The ratio of the phenotypes will be 6:6:2:2, or 3:3:1:1 (long-winged red eye: long-winged white eye: vestigial wing red eye: vestigial wing white eye), genotypes shown in the attachment.

c. F1 cross back to the mother would be Vg+VgXRY x Vg+Vg+XrXr. The genotypes are shown in the attached punnet square. The offspring will all be long-winged with white eyes. The F1 to the father would be Vg+VgXRXr x VgVgXRY. The ratio would be 3:3:1:1 long-winged red eye: long-winged white eye: vestigial wing red eye: vestigial wing white eye

Download docx
7 0
3 years ago
How do seabirds get caught in fishing nets ?
Liula [17]

Answer:

Mammals are usually caught in nets, but long line fishing catches more than just target species of fish. Sharks, turtles and seabirds are all attracted to the bait on the lines of long line fishing. Seabirds get caught on the lines and drown.

Explanation:

5 0
3 years ago
Read 2 more answers
What are domains in biology? Question 8 options: internet website classification system highest ranking of organisms in taxonomy
lora16 [44]

Domain is the highest ranking of organisms in taxonomy.

The correct option is b.

<h3>What do you mean by domain?</h3>

Domain is the highest ranking of the biological system.

In the system there are three domains

  • Archaea
  • Bacteria
  • Eukarya

This is the highest classification, after this further classification of living organism is done.

Thus, the correct option is B

Learn more about domain

brainly.com/question/1634690

7 0
2 years ago
Give 3 examples how meiosis differ from mitosis.
kkurt [141]

Answer:

Examples of cells that are produced through mitosis include cells in the human body for the skin, blood, and muscles.

Explanation:

In this case cells go through different phases called the cell cycle. The "normal" state of a cell is called the "interphase". The genetic material is duplicated during the interphase stage of the cell.

8 0
2 years ago
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to:a. add m
Simora [160]

Answer:

a. add more of the enzyme

Explanation:

Enzymes have specific sites to which their substrates bind during the reaction. These sites are called active sites. When all the active sites of all the enzyme molecules present in a solution are bound to the substrate molecules, the enzyme is said to be saturated with the substrate. Under these conditions, more enzyme molecules are to be added to the solution to increase the reaction rate and to obtain the product at a fast rate. The addition of more enzymes will allow more substrate molecules to occupy the active sites and to be converted into the product/s.

4 0
3 years ago
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