1. Reproductive Strategies Life Science #1 and #2

2. Vocabulary Asexual Reproduction Asexual Reproduction Dominant Trait Dominant Trait Gene Gene Heredity Heredity Recessive Trait Recessive Trait Sexual Reproduction Sexual Reproduction Variation Variation

3. What Do You Think? All plants and animals have traits, or characteristics, that pass from one generation on to the next. All plants and animals have traits, or characteristics, that pass from one generation on to the next. If individuals survive, the species survives. If individuals survive, the species survives.

4. What Do You Think? When a bacterium reproduces, the offspring are exact copies of the parent bacterium and each other. Under what conditions do you think this strategy would help a species continue on to the future. When a bacterium reproduces, the offspring are exact copies of the parent bacterium and each other. Under what conditions do you think this strategy would help a species continue on to the future. __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________

5. What Do You Think? When rabbits reproduce, the offspring are slightly different from the parents and each other. Under what conditions do you think this strategy would help a species continue into the future? When rabbits reproduce, the offspring are slightly different from the parents and each other. Under what conditions do you think this strategy would help a species continue into the future? __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________ __________________________________

6. Heredity Heredity refers to the passing of traits from parent to offspring. Heredity refers to the passing of traits from parent to offspring. Tiny molecules called genes control the traits that appear in those offspring. Tiny molecules called genes control the traits that appear in those offspring. Each gene is a small piece of DNA, arranged into chromosomes. Each gene is a small piece of DNA, arranged into chromosomes.

7. Sexual Reproduction The offspring of sexual reproduction have two parents. The offspring of sexual reproduction have two parents. Reproduction occurs when two gametes (one from each parent) fuse together. Reproduction occurs when two gametes (one from each parent) fuse together. –Gametes have ½ of the normal amount of chromosomes. –The normal amount is 46, gametes have 23. –This is how you get traits from both parents.

8. Sexual Reproduction An organism with 8 chromosomes reproduces sexually. An organism with 8 chromosomes reproduces sexually. The diagram shows two gametes joining. The diagram shows two gametes joining. Complete the diagram to show the process of fertilization. Complete the diagram to show the process of fertilization.

9. Sexual Reproduction A species that reproduces sexually typically shows a lot of variation among its members. A species that reproduces sexually typically shows a lot of variation among its members. This is because different combinations of genes leads to different combinations of traits. This is because different combinations of genes leads to different combinations of traits.

10. Sexual Reproduction The new combinations of traits that result from sexual reproduction can increase or decrease an individual’s chances for survival. The new combinations of traits that result from sexual reproduction can increase or decrease an individual’s chances for survival. –A cardinal with strong wings and a weak beak mates with a cardinal with weak wings and a strong beak. Which combination of traits would be the most beneficial to the survival of their offspring? –____________________________________

11. Asexual Reproduction In asexual reproduction, the offspring has one parent that multiplies without using seeds, gametes or fertilization. In asexual reproduction, the offspring has one parent that multiplies without using seeds, gametes or fertilization. The offspring of asexual reproduction are almost always exact genetic copies of the single adult parent. The offspring of asexual reproduction are almost always exact genetic copies of the single adult parent. –Name one organism that reproduces asexually. –____________________________________

12. Asexual Reproduction Many single-celled organisms reproduce by binary fission. Many single-celled organisms reproduce by binary fission. This is where a cell duplicated its chromosomes, then divides into two cells. This is where a cell duplicated its chromosomes, then divides into two cells. Each new cell is an exact copy of its parent. Each new cell is an exact copy of its parent.

13. Asexual Reproduction An organism with 8 chromosomes reproduces by binary fission. An organism with 8 chromosomes reproduces by binary fission. Complete the diagram to show how the chromosomes are distributed. Complete the diagram to show how the chromosomes are distributed.

14. Asexual Reproduction Some offspring of asexual reproduction have mutations. Some offspring of asexual reproduction have mutations. This means that they have some trait that their parent does not have. This means that they have some trait that their parent does not have. –This trait can be helpful or harmful, increasing or decreasing its chance for survival. Mutations are rare, and most are harmful. Mutations are rare, and most are harmful.

15. Asexual Reproduction An advantage of asexual reproduction is that it limits the spread of harmful traits in a species. An advantage of asexual reproduction is that it limits the spread of harmful traits in a species. It also leads to genetic continuity in a species. It also leads to genetic continuity in a species. –This means that many generations may all have the same genetic makeup.

16. Asexual Reproduction If many generations have the same genetic makeup, this can be helpful or harmful to the species. If many generations have the same genetic makeup, this can be helpful or harmful to the species. –If there are not any changes in the environment, the species does not need genetic diversity. –However, if there is a permanent environmental change, and one individual is unable to survive, then the whole species will be wiped out.