Orcas are sometimes called the "wolves of the sea." They are predators; they prey on other animals for food. Like wolves, they w
ork together in groups. If you're a porpoise or a big fish, you should watch out for an orca. If you're an orca, then you hope that the porpoise or big fish doesn't get away. If it does, then you have to go hungry. What is the main idea of the paragraph?
A.
Orcas are predators.
B.
Orcas are harmless.
C.
Orcas chase big fish.
D.
Orcas live in groups
The answer is A. The entire paragraph shows that orcas eat other animals, and that the smaller animals should stay away from the orcas, showing that they are the prey.
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism.
