Answer:
D. The scientist uses tennis balls to show the position of the planets and Sun.
Explanation:
In a layman's terms, the solar system is a system consisting of the sun and the planets that orbits around it. These planets are as follows; Mercury, Mars, Earth, Saturn, Venus, Jupiter, Neptune, Uranus etc.
According to this question, using a physical model to represent or describe the solar system means the use of physical objects that can easily be seen or identified. Based on this explanation, the use of tennis balls to show the position of the planets and Sun suits the physical model description of our solar system.
Answer:
Answer: B: allowing a forest to grow wildly
Explanation:
The other ones (A & C) Have Human interaction, B explains that you are leaving the Environment alone, not building anything, not cutting anything, but letting nature take its course.
Answer:
It decreases the oxygen content of the atmosphere and can increase CO2 contant.
Explanation:
Answer: the control group was grown at a pH of 2
Explanation:
Seeds comprise a radicle, which descends and becomes the root system; the endosperm, containing stored food; an epicotyl, which develops into the stem and the seed coat that protects the seed. which are small food storage organs and plant embryos encased in a seed coat. These embryos require specific conditions in order to break their dormancy; seed dormancy is a temporary state in which plant development and growth are halted, until specific conditions required for germination to occur. Conditions required for seed germination:
- Light- some seeds require light to break their dormancy
- Oxygen- for respiration
- Water- protein hydration and enzyme activation; should be near to neutral pH
- Temperature- a specific range 20-30 °C which activates specific enzymes needed for growth
During the germination process, plants emerge from the seed and start growing. However, the delicate tissue structures can be damaged by low pH; this can occur due to acid rain, where the pH of the rainwater is lowered by the presence of pollutants.
Due to the presence of atmospheric carbon dioxide, normal rain’s pH is typically around 5.6, and in heavily polluted areas with other gases as pollutants, acid rain’s pH can range from 3-4. A highly acidic pH of 2 can denature enzymes required for germination and seed growth; apart from causing damage to the entire seed, there’s no expected growth at this pH range making it a suitable control.
Experimental controls give valuable information about the experiment’s conditions and validity; they are usually carried out in the same conditions as the other experiments, but the independent variable (pH) is usually changed.
