The Earth's atmosphere would have little or no oxygen. A by-product of photosynthesis is oxygen. Photosynthesis is the process by which green plants use energy from the sun to make their own food in the leaves. The process uses sun light, water and carbon dioxide to yield oxygen and simple sugars. The simple sugars are stored in form of starch for future use by the plants, while oxygen is either used for cellular respiration or released to the atmosphere. The process of photosynthesis adds oxygen to the atmosphere and uses carbon dioxide from the atmosphere.
The second question has the answer of A
1. outer covering - none of the other answers can occur due to the absorbed solutions inability to reach the centre of the organism, smaller cells in greater numbers are more efficient as they can group together yet all absorb the right amounts of nutrients for its need. multi cellular organisms, such as humans can have the other answers in them as cells group together to make skin, muscles and organs. it also gives the organism to grow larger.
2. bacteria are single celled. bacteria reproduce through mitosis (cell division). bacteria break down decaying matter to obtain energy. every organism requires energy to live. Bacteria can move in order to reach their nutrient source.
