Chapter 7, Problem 3A

Summary Introduction

To replace:

The italicized word with a correct vocabulary term in the given sentence

Introduction : For many centuries, scientists had no idea our body is made of millions of cells. Only after the invention of microscope, they were able to see cells in living things. Robert Hooke was the first one to use the term ‘cell’. A cell is the structural and functional unit of all living organisms.

Answer to Problem 3A

Cells are basic units of all organisms.

Explanation of Solution

According to the cell theory, cells are the basic units of all living organisms. Cells exist in all shapes and sizes. They differ in the kind of function they perform for the organism. All cells have a special membrane called plasma membrane that acts as a boundary.

Each cell has different organelle to perform specific tasks. A cell is involved in many functions such as energy transformations, food digestion, excretion of wastes and cell division.

There are two broad categories of cells; prokaryotic cells and eukaryotic cells. Prokaryotes do not have membrane bound organelles while eukaryotes have membrane bound organelles.