Reproduction No organism lives forever. Even the oldest tree will eventually die one day. In order for each species, or type of organism, to continue, its members must reproduce. This is just as true for simple, unicellular organisms as it is for the most complex, multicellular organisms. Why is it important for individuals in a species to reproduce? _______________________________________________ _______________________________________________

Asexual Reproduction Traits of the offspring are exactly the same as the parent. Identical DNA to the parent Many types of asexual reproduction

Asexual Reproduction cont’d Unicellular organisms, like bacteria, simply copy their DNA. Then they split into two identical halves.

Asexual cont’d New plants can be produced from certain sections of an existing plant. Fragments of simple animals, like earthworms, can also reproduce a new organism identical to its parent. For example, if certain sections of an earthworm are cut off, they can regenerate the entire organism.

Asexual cont’d What is asexual reproduction? ________________________________________ ______________ Identify two examples of asexual reproduction: 1__________________2_________________

The consequences of asexual reprodcution--Advantages Inherited traits from a single parent are preserved for genetic continuity This limits the spread of detrimental characterisitics in a species If there are unfavorable traits, the organism cannot live in its environment and will die…not pass down unfavorable traits to further offspring since dead Can multiply without having to seek out a mate

Consequences cont’d-- Disadvantages New combinations of traits rarely occur w/asexual reproduction. The same genes continually reproduce themselves. If the environment changes, the species may find it very difficult to adapt to the new conditions. List one advantage and one disadvantage of asexual reproduction: Advantage_______________________________ _ Disadvantage_____________________________

Sexual Reproduction Two parents are required Offspring inherits some of its traits from each parent Never identical to either one of its parents

How sexual reproduction works… Sex cells are used to pass traits to offspring Females have eggs Males have sperm When a male and a female sex cell joins from the same species, an offspring is created