Life Cycles
Before we go into life cycles, we need to understand the two types of reproduction: asexual and sexual.
Asexual Reproduction: In this form of reproduction, a single parent gives rise to offspring through mitosis. All of the parent's genes are directly passed onto its offspring, thereby creating identical clones of itself. Not only do the offspring have the exact same features as the parent, they also have identical chromosomes. This form of reproduction is usually found in primitive organisms, such as sponges, bacteria, and some protists. Mechanisms of asexual reproduction include binary fission, budding, fragmentation, etc. There is little genetic variation among the offspring of such organisms; variations are most likely due to mutations. Sexual Reproduction: This is the more complex form of reproduction. Different parents produce gametes through meiosis, which are fused to form zygotes. Because the gametes carry genetic information, the offspring inherit their genes from both parents. Most animals and plants reproduce this way. The main focus of this entire unit is to determine which genes will be expressed by the offspring and why. |