To put it simply, ionic bonds form when one atom transfers an electron to another atom. The atom that gains an electron becomes a negative ion while the atom that loses an electron becomes a positive ion. Covalent bonds form when two atoms share electrons. A hydrogen bond is when you have a negatively charged O, N, or F atom in one molecule, a positively charged H atom latched on to an O, N or F atom in another molecule. An example of a hydrogen bond is water.
Plant cell needs cell wall whereas animal cell do not because the plants need rigid structure so that they can grow up and out . All cells have cell membranes, and the membranes are flexible. So animal cells can have various shapes, but plant cells only have the shapes of their cell walls.
D is gonna be your answer because the more animals the more competition for survival
Answer:
if anaerobic activity takes place over a long period of time the muscles soon become exhausted
Because it has no scientific explanation. As a matter of fact it has no explanation.
The things that black cats cause bad luck are a myth, and do not have any proof or explanation, meaning it cannot be concluded neither as a hypothesis nor scientific.
Hope it helped,
BioTeacher101
