Amedical researcher experimented with the effects of calcium intake on the healing time of broken bones. people who had similar broken bone injuries were divided randomly into two groups, one of which received a calcium supplement and one of which received a placebo. the data showed that there was no significant difference in healing times between the two groups, so the researcher concluded that calcium intake has no effect on bone healing time. why is the conclusion of the researcher not justified?

The correct answer will be- due to lack of control group.

Explanation:

A scientific experiment is performed to test the proposed hypothesis by including the variables as well as diving the samples into an experimental and control group.

In the experimental group, the independent variable directly influences the dependent variable whereas the independent variable does not influence the dependent variable.The control group act as a reference to the experimental group.

In the given question, although the experimenter divided the group into two groups but he did not add a control group in the experiment with no calcium and even placebo drug effect.

Thus, due to the lack of a control group is the correct answer.

stratosphere: as the altitude increases, the air temperature increases. the stratosphere has a layer of ozone, called the ozone layer. this layer absorbs most of the ultraviolet radiation from sunlight. this results in the stratosphere being warmer.

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).