Your Body. How It Works. The Reproductive System PDF Free Download
The fact that this book is not a living organism should not be much of a surprise to anyone over the age of five. But how do we know that it is an inanimate object? The scientific community has developed a list of characteristics that can be used to determine if an object is truly alive. One of those characteristics is the ability to reproduce, ensuring the continued existence of the organism’s population. Although this book was reproduced many times on a printing press, the book itself has no self-regulating mechanism to reproduce its own pages. However, all living organisms, from a single-celled amoeba to a 72 trillion-celled human have an innate drive to reproduce. It is a drive, not just a desire. Drive is something that must at least be tried if not accomplished. There are two kinds of reproduction: asexual and sexual. Many biochemical events must occur before an organism can reproduce either way. Asexual reproduction is the simplest form of reproduction. Asexual literally means “without sex.” In organisms that reproduce asexually, there are no males or females and reproduction occurs without partners coming together. Asexual, single-celled animals grow to a certain stage or size and will then divide into two identical organisms. This division is a complex process, requiring the organized division of genetic material, mitosis (Figure 1.1), to be coordinated with the division of the cytoplasm, cytokinesis, to form the daughter cells.