Which layer of the atmosphere contains a substance that was created from a product of living things and that protects living things

7th grade question (easy) look at the diagram of the food web. the arrows mean eaten by. what would happen if the number of snakes went down? answer choices are in the image.

The smallest parts of these that retain their original properties are called

Need asap plz hurry im being timed when a body cell divides through the process of mitosis, the chromosomes in the daughter cells a. represent only the healthiest chromosomes from the parent cell. b. represent only half of the chromosomes in the parent cell. c. are identical to the chromosomes of the parent cell. d. are formed when chromosomes from the parent cell cross over.