Which of the following statements about pattern formation are true

Question 1

Which Of The Following Statements About Pattern Formation Are True?

1) Homeotic genes code for transcription factors that control the development of segment-specific body parts.

2) Homeotic genes establish major body axes.

3) Cells receive molecular signals that communicate their position in relation to other cells.

4)Differential gene expression affects the developmental process in animals.

5)Pattern formation begins in adult animals.

6)The process of pattern formation involves segmentation of the body but does not involve the development of segment-specific body parts.

7)Positional information controls pattern formation.

Question 2

Which of the following statements is true of an explanatory hypothesis?

A. It includes the presumption of causation.

B. It makes no statement with respect to causation.

C. It’s correlated, but not causal.

D. It excludes the presumption of causation.

Question 3

Which of the following is true?

A. ectoderm is characteristic of the morula

B. endoderm is formed during fertilization

C. mesoderm is associated with connective tissues

D. organogenesis occurs in the pre-embryonic stage

E. All of the above are correct.

Answer to question 1

1. Homeotic genes code for transcription factors that control the development of segment-specific body parts. The given statement is true. The homeotic genes specify the kind of appendages or structures develop in a specific segment. These  genes encode  the transcription factors that regulate the expression of genes.

2. Homeotic genes establish major body axes. Flase. The bicoid genes during development of embryo and other group of maternal effect genes establishes the dorsal – ventral axes of the body.

3. Cells receive molecular signals that communicate their position in relation to other cells. True. Induction is the signaling from one group of cells to another that brings about differentiation.

4. Differential gene expression affects the developmental process in animals. True. Embryonic development involves cell division, cell differentiation, and morphogenesis. Cells also become specialized in structure and function. This is called differentiation. As cells differentiate, they become arranged in tissues and organs. The physical processes that give an organism its shape constitute morphogenesis.

5. Pattern formation begins in adult animals. False. Pattern formation in animals begins in the early embryo, when the animal

Answer to question 2

The correct answer is A. It includes the presumption of causation .

Explanatory hypothesis gives explanations and reasons behind the formation of meaningful patterns. This hypothesis describes how predictions come out and patterns are formed.

A true statement regarding the explanatory hypothesis is “It includes the presumption of causation.” Presumption means forming assumptions to believe a condition is actual, but in reality, that condition is still not proved true. Ideas are taken as a base in developing a presumption.

Causation means finding the cause and effect behind an event. The findings and results are essential in forming a hypothesis.

The explanatory hypothesis consists of the presumption of causation as an individual uses the idea to find reasons behind an issue. After determining the relationship between a problem and its observations, a hypothesis is produced. To prove a hypothesis, researchers provide accurate predictions.

Reasons for incorrect options:

Option B is incorrect because it is invalid to say that the explanatory hypothesis does not make a statement concerning causation. This form of hypothesis makes statements and predictions related to causation.

Option C is incorrect because an explanatory hypothesis is correlated, but not causal is not sensible. The explanatory theory is correlated along with the causality. The cause and effect are necessary to determine the actual reason behind a problem.

Option D is incorrect because the explanatory hypothesis does not exclude the presumption of causation. This hypothesis includes it.

Answer to question 3

Which of the following is true?

C. mesoderm is associated with connective tissues

Mesoderm is the central germinal layer which is in-between outer ectoderm and inner endoderm. It is responsible for the formation of bone, muscles, blood vessels and connective tissues.

Below are wrong options:

A. ectoderm is characteristic of the morula: Ectoderm is not formed at the morula stage.

B. endoderm is formed during fertilization: Fertilization is a process in which the haploid gametes (sperm and egg) fuse to form a zygote (diplod). Endoderm is not yet formed during the fertilization.

D. organogenesis occurs in the pre-embryonic stage: organogenesis is the last stage of embryo development where the germ layers develop into organs of the body

E. All of the above are correct: not true

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