Direction for the following 4 (four) items: Read the following four passages and answer the items (11-14) that follow. Your answers to these items should be based on the passages only.

Researchers were able to use stem cells to gauge the neurotoxic effects of the environmental pollutant Bisphenol A (BPA). They used a combination of biochemical and cell-based assays to examine the gene expression profit during the differentiation of mouse embryonic stem cells upon treatment with BPA, a compound known to cause heart diseases, diabetes, and developmental abnormalities in humans. They were able to detect and measure BPA toxicity towards the proper specification of primary germ layers, such as endoderm and ectoderm, and the establishment of neural progenitor cells.

On the basis of the passage given above, the following assumptions have been made:
1. BPA may alter embryonic development in vivo.
2. Biochemical and cell-based assays are useful in finding out treatments for pollution-induced diseases.
3. Embryonic stem cells could serve as a model to evaluate the physiological effects of environmental pollutants.
Which of the above assumptions are valid?

The correct option is 1 and 3 only.

Let us analyze each assumption based strictly on the provided passage:

Assumption 1: "BPA may alter embryonic development in vivo."
This assumption is valid. The passage explicitly states that BPA was detected to cause toxicity towards the "proper specification of primary germ layers, such as endoderm and ectoderm, and the establishment of neural progenitor cells." Furthermore, BPA is noted for causing "developmental abnormalities in humans." Thus, it is reasonable to assume that BPA may alter embryonic development in living organisms (in vivo).

Assumption 2: "Biochemical and cell-based assays are useful in finding out treatments for pollution-induced diseases."
This assumption is invalid. The passage mentions that researchers used biochemical and cell-based assays to "examine the gene expression profit during the differentiation of mouse embryonic stem cells upon treatment with BPA" and to "gauge the neurotoxic effects" / "detect and measure BPA toxicity." It discusses measuring toxicity and effects, not finding treatments or cures for pollution-induced diseases.

Assumption 3: "Embryonic stem cells could serve as a model to evaluate the physiological effects of environmental pollutants."
This assumption is valid. The entire passage describes how researchers successfully used "mouse embryonic stem cells" to "gauge the neurotoxic effects of the environmental pollutant Bisphenol A (BPA)." This directly supports the assumption that embryonic stem cells can serve as an effective model for evaluating such environmental pollutants.

Therefore, only assumptions 1 and 3 are valid, making 1 and 3 only the correct answer.