Answer:
The nucleus, cell membrane and cytoplasm.
Explanation:
The nucleus, cell membrane and cytoplasm are three elements that cannot be absent in a cell because they are necessary for the survival of the cell. The nucleus controls and regulates the activities happening inside the cell e.g. growth and metabolism etc. Cell membrane acts as a wall to protect the inner part of the cell from the external environment as well as allows nutrients and gases inside and outside the cell. Cytoplasm serves as a medium for the conduction of nutrients and waste from on place to another and also for the medium for organelles in which they floats.
Answer:
Enzymes help speed up chemical reactions in the human body. They bind to molecules and alter them in specific ways. They are essential for respiration, digesting food, muscle and nerve function, among thousands of other roles.
Explanation:
Answer:
Fracking can contaminate water supplies if it is not done properly, because the fracking fluid injected into rock to enable gas to be released often contains chemicals. If the borehole is not properly cased to stop leaks, the fracking water can escape into the aquifer
Answer: corpus luteum secretion
Explanation:
<span>Choices (b) and (c) are the most correct. Bilateral symmetry requires a central axis for there to be two halves. In addition, this type of symmetry requires a head, which will encounter the environment before any other part of the body and move in the direction of travel. Most animals exhibit this characteristic.</span>