Biology

Life Cycles and Reproductive Strategies

Bill Nye the Science Guy episode 86: Search for “Bill Nye life cycles” if the link wont work; watch the first 11 minutes. https://www.youtube.com/watch?v=VNIR3lsJwuk

1.  What are the four stages of a life cycle (according to Bill Nye)?

2. What is a “spore”? What is a “seed”? What is an “egg”? How are they all similar?

3. What are “K-Selected” species? What is their reprductive stragedy? Give an example.

4. What are “r-selected” species? What is their reproductive strategy? Give an example.

5. Why would different species have different lengths (time) in their life cycles?

Thinking Questions

1. What does the word “cycle” mean?

2. Is there anything wrong or confusing about Bill Nye’s explanation of “life cycle”?

3. Is there a better way to describe a life cycle?

Follow-Up Questions

*(I’VE ATTACHED THE GRAPH TO A PDF FILE, PLEASE USE IT TO ANSWER THESE QUESTIONS BELOW)*

1A classic study was conducted following the changing populations of the snowshoe hare and the lynx in Canada.

a. Why would the snowshoe hare population “crash” every seven to ten years?

b. Why are the lynx population’s fluctuations approximately a year behind the snowshoe hares’?

c. Where do YOU think the carrying capacity is for the hare? Sketch on the graph. (you can highlight the parts on the graph using word doc.)

d. Where do YOU think the carrying capacity is for the lynx? Sketch on the graph.(you can highlight the parts on the graph using word doc.)

2. Population density, i.e. the number of individuals in a population found within a defined area, can have a profound affect on population growth patterns. For example, in a dense population, parasites and disease have a greater effect on population size (and its growth patterns). Why would population density affect population size?

3. In nature, elimination of a predator in an ecosystem can cause the elimination of its prey species! This seems counterintuitive, if the predator is removed, shouldn’t the prey increase? Explain how/why the prey could decrease when its predator is eliminated. Does this happen immediately? Or does it take awhile?