Correct Answer: A

Rationale: The correct answer is 'Temperature.' In an experiment, the independent variable is the factor that is deliberately manipulated or changed by the researcher. In this study, the botanist is specifically investigating how environmental temperature affects root growth, making temperature the independent variable. Choice B, 'Seedlings,' and Choice C, 'Light,' are not the independent variables in this context as they are not the factors being intentionally changed or manipulated. Choice D, 'Root length,' is the dependent variable, as it is the outcome that is being measured or observed in response to the changes in the independent variable, temperature.

Correct Answer: B

Rationale: In the scientific method, defining the problem is typically the initial step. Before gathering qualitative data, it is essential to clearly outline and understand the issue or question being addressed. This step helps in guiding the research process and ensures that the data collected are relevant to the problem at hand. Communicating with a scientific journal (Choice A) is not a standard step in the scientific method; it comes after the research is conducted. Developing a hypothesis (Choice C) usually follows defining the problem and precedes data collection. Categorizing data for statistical analysis (Choice D) occurs after data collection, not before gathering qualitative data.

Correct Answer: B

Rationale: The correct answer is B, the Scapula. Flat bones, such as the scapula, are thin, flattened bones that provide protection to internal organs and serve as attachment points for muscles. The other choices, femur, humerus, and tibia, are examples of long bones, which are characterized by their elongated structure and are primarily involved in supporting weight and facilitating movement.

Correct Answer: D

Rationale: When blood sugar levels drop in the body, the pancreas releases glucagon. Glucagon acts to increase blood sugar levels by stimulating the liver to release stored glucose into the bloodstream. Therefore, the correct answer is D. Choice A is incorrect because the release of insulin lowers blood sugar levels, opposite of what happens when blood sugar is dropping. Choice B is incorrect as the liver releases stored glucose in response to low blood sugar, not when blood sugar is already dropping. Choice C is also incorrect as the liver stores glucose as glycogen but doesn't directly impact blood sugar levels dropping in the moment.

Correct Answer: B

Rationale: The rib cage plays a crucial role in protecting vital organs, specifically the lungs and heart, from external injuries. Choice A is incorrect because the rib cage does not primarily protect the digestive organs. Choice C is incorrect as the primary function of the rib cage is not to support movement, but to protect internal organs. Choice D is incorrect as regulating body temperature is not a function typically associated with the rib cage.