For each event or condition described below, match the correct answer to the following questions.? Populations evolve for many r
easons. Suppose there is a population of plants that have either purple flowers or white flowers, and the allele for purple flowers is dominant. This means that plants with two purple alleles have purple flowers. Plants with one purple allele and one white allele also have purple...
Populations evolve for many reasons. Suppose there is a population of plants that have either purple flowers or white flowers, and the allele for purple flowers is dominant. This means that plants with two purple alleles have purple flowers. Plants with one purple allele and one white allele also have purple flowers. Only plants with two white alleles have white flowers.
<span>Which mechanism of evolution is at work? </span> <span>How does this event affect the population’s gene pool? Do the frequencies of the two alleles change, and if so, how? </span>
<span>1.During an extreme heat wave, plants with white flowers survive better. </span>
<span>2. Workers from a nearby greenhouse accidentally introduce white flower seeds into this population's habitat </span>
<span>3.A storm kills many plants at random. </span>
<span>4. A person uproots the five closest plants, all of which happen to have white flowers. </span>
<span>A. Mechanism is gene flow and frequency of white allele increases </span>
<span>B. Mechanism is genetic drift and allele frequencies stay the same </span>
<span>C. The mechanism is genetic drift and allele frequencies change but not predictably. </span>
<span>D. Mechanism is genetic drift and the frequency of the purple allele increases. </span>
<span>E. Mechanism is Natural Selection and frequency of white allele increases </span>
<span>F. Mechanism is gene flow and allele frequencies change but not predictably. </span> The answers are the below:
<span>Gene flow: genes from one population are transferred to a different population Genetic drift: random changes of allele frequency within a population from one generation to the next Natural Selection: a test of the fitness of an organism to survive and reproduce in a specific environment.
1:E - Heat kills more purple plants, total white alleles increase. Natural selection because the white plants are more suited to their environment (ie they die less) than purple plants.
2:A - Gene flow because genes from one population (the greenhouse) are introduced into another population (the general population). White alleles increase because now there are more white seeds than before.
3:C - Genetic drift because the plants that die are random color. The frequency is likely to change (although it could stay the same, but it's unlikely) but you don't know how it changes unless you know which plants died.
4:D - Genetic drift because (presumably) the plants were chosen at random. And the amount of white alleles decrease because it was white flowers that died.</span>
Gizmono NASA reignited our hopes of finding alien life when it announced the first direct evidence of liquid water on Mars. But before we start indulging in fantasies of space crabs and reptilian beings, we ought to remember that Mars is a frigid world with a thin atmosphere. And that raises an obvious question: What sorts of life forms could actually live there?
Any life on Mars today is almost certainly microbial, but beyond that, we can’t be sure of anything until we actually dig it up and study it. Still, we can make some educated guesses about the nature of Martian life, by taking a deep dive into some of the weirdest biology on planet
Answer: An independent variable, sometimes called an experimental or predictor variable, is a variable that is being manipulated in an experiment in order to observe the effect on a dependent variable, sometimes called an outcome variable.
Explanation: Example: What is a good outcome variable for deciding whether cancer treatment in a country has been improving?
A first thought might be "number of deaths in the country from cancer in one year." But number of deaths might increase simply because the population is increasing. Or it might go down if cancer incidence is decreasing. "Percent of the population that dies of cancer in one year" would take care of the first problem, but not the second.
This example makes the point that a rate is often a better measure than a count.
