1. Asexual vs Sexual Reproduction
Biology Notes 3
Asexual vs Sexual Reproduction

2. Asexual Reproduction Only one parent is required
Offspring are genetically identical to parent - clone (Mitosis)
Lacks variation in a species (they all look alike) – Could this be a detriment to the population?

3. Examples of Asexually Reproducing Organisms
Bacteria
Bread mold
Tree shoots

4. Types of Asexual Reproduction Page 154-161
Binary fission
Budding
Fragmentation
Vegetative reproduction
Spore formation

5. Binary Fission
A single parent cell replicates its genetic material and divides into two equal parts.
Ex: amoeba, bacteria, algae, protozoa

6. Budding
When part of the yeast cell pushes outward to form an outgrowth or bud. The bud then pinches off from the parent cell to become a yeast cell identical to the parent.
In the case of the hydra and sponge the bud may not detach from the parent.
Ex: yeast, hydra, sponge

7. Fragmentation
If an organism breaks apart as a result of injury, each fragment then develops into a clone of its parent
Ex: Sea Star, Plants “Japanese Knotweed”

8. Vegetative Reproduction
Special cells usually in plant stems and plant roots divide repeatedly to form structures that will eventually develop into a plant identical to the parent
Ex: tulips, strawberry runners, potato sprouts or eyes, plant cutting

9. Spore Formation
A spore is a reproductive cell that grows into a new individual by mitosis. Spores are lightweight, and can be carried by wind or water to a new location. If the new location has the right conditions (food, temperature, moisture) for growth, the spore can start growing immediately.
Ex: molds

10. Advantages of Asexual Reproduction
Large numbers of offspring are produced quickly
Large colonies can form that can outcompete other organisms for nutrients and water
Large numbers of organisms mean that species may survive when conditions or the number of predators change
Energy is not required to find a mate

11. Disadvantage of Asexual Reproduction
Offspring are genetic clones. A negative mutation can make asexually produced organisms susceptible to disease and can destroy large numbers of offspring.
Some methods of asexual reproduction (ex: strawberry plants) produce offspring that are close together and compete for food and space.
Unfavourable conditions such as extreme temperatures can wipe out entire colonies.

12. Sexual Reproduction Requires two parents
Produces offspring that are genetically different from their parents.
Greater variation in a species.

13. Sexual Reproduction Involves
The fusion of an egg cell and a sperm cell to produce a zygote

14. External Fertilization
most aquatic organisms, mosses (read Pg 184) and ferns
Sperm cell and egg cells of the same species unite outside the bodies of the parents. Ex: salmon (both the male and female parents die after spawning
Ex: Moss – water transports their gametes enabling them to meet. The male and female sex organs develop on the end of the branches of the plants. Fertilization happens by the sperm cells being splashed by raindrops into the female part of the plant.

15. External fertilization provides an advantage because very little energy is required to find a mate, and large numbers of offspring are produced at one time creating a greater chance of survival during an environmental disaster. A disadvantage is that the eggs are unprotected and often preyed upon. Since parents do not care for their offspring, few survive to adulthood.

16. Internal Fertilization
Whales and most land dwelling animals such as moose and humans.
Sperm cells are deposited inside the females body where they meet an egg cell
Embryo develops inside the mothers body for a period of time protecting it from predators

17. Pollination in Flowering Plants

18. Pollen Transport Bees Wind Water
Other animals fur or by eating the fruit (seeds have a tough outer coat and often do not get digested by animals)
Activity page 191

19. Sexual Reproduction in Insects (Grasshopper & Butterfly)
The male deposits a package of sperm inside the female to fertilize the eggs. The female then deposits the fertilized eggs in a protected area under a leaf or in a burrow. Eggs develop and eventually hatch on their own, when conditions are right.
Insects often change form between hatching and adulthood this is called metamorphosis

20. Grasshopper – Incomplete Metamorphosis
Involves subtle changes through three life stages – egg, nymph, and adult

21. Butterfly Complete Metamorphosis

22. Advantages of Sexual Reproduction
Very little energy is required to find a mate (external fertilization)
Greater numbers of offspring can repopulate an area after a disaster
More protection and parental care is given to young
Offspring are genetically different from their parents so they may survive new diseases or other threats that appear in a population

23. Disadvantages of Sexual Reproduction
More energy is required to find a mate (internal fertilization)
Fewer offspring are produced, so if the number of predators increases, a population will decline (internal fertilization)
Gametes, embryo’s, and offspring are unprotected and are often preyed upon (external fertilization)
Some beneficial traits may not be passed on from parents to offspring

24. Study Chart: Asexual vs Sexual Reproduction
Asexual Reproduction
Sexual Reproduction
Number of Parent Cells
Gametes (eggs or sperm)
Variation in offspring
Amount of energy required
Parental Care
Mitosis or Meiosis?