A control group in a scientific experiment is a group separated from the rest of the experiment, where the independent variable being tested cannot influence the results. This isolates the independent variable's effects on the experiment and can help rule out alternative explanations of the experimental results.
Darwin’s Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources. This illustration shows the beak shapes for four species of ground finch: 1. Geospiza magnirostris (the large ground finch), 2. G. fortis (the medium ground finch), 3. G. parvula (the small tree finch), and 4. Certhidea olivacea (the green-warbler finch) the Grants measured beak sizes in the much-reduced population, they found that the average bill size was larger. This was clear evidence for natural selection of bill size caused by the availability of seeds. The Grants had studied the inheritance of bill sizes and knew that the surviving large-billed birds would tend to produce offspring with larger bills, so the selection would lead to evolution of bill size. Subsequent studies by the Grants have demonstrated selection on and evolution of bill size in this species in response to other changing conditions on the island. The evolution has occurred both to larger bills, as in this case, and to smaller bills when large seeds became rare.

Answer:
Have different numbers of neutrons
Explanation:
Isotopes of an element have different atomic numbers because thy differ in neutron number even though proton number remains the same across the isotopes. The mass number is the summation of the proton and neutron number. Phosphorus has approximately 23 isotopes whose mass number range between 25 and 47. Only ³¹P is stable.
Answer:
Forests. Photosynthesis removes carbon dioxide naturally — and trees are especially good at storing carbon removed from the atmosphere by photosynthesis
Explanation:
Plants are involved in the Carbon Cycle by absorbing Carbon out of the atmosphere in order to photosynthesize. The Carbon is used during the photosynthesis. It gets back in the environment by a plant's breathing process.