What is the independent, dependant, and controlled variable for the following experiments.
experiment 1
part 1:
two people are shown talking about how much they like iced tea. person 1 argues that iced tea is better at room temperature (i. e., 20℃). person 2 argues that iced tea is better at 0℃. to settle their argument, they decide to reduce the temperature of a pitcher of iced tea from 20℃ to 0℃ and compare the taste at both temperatures.
the video pauses here to allow students to hypothesize what will happen as the temperature of the iced tea is reduced from 20℃ to 0℃.
part 2:
the people place a thermometer inside a pitcher of iced tea and then place the pitcher inside a freezer. when the pitcher first goes into the freezer, the thermometer reads −20℃.
gradually, show the thermometer’s red line (or the number, if it’s a digital thermometer) dropping from 20℃ to 0℃.
when the thermometer reads 0℃, the people should remove the pitcher from the freezer. one person should attempt to remove the thermometer, only to find that the iced tea has frozen and the thermometer is stuck.
experiment 2
part 1:
a chef is shown stirring salt and other seasonings into a pot of soup that is resting on a stove burner. the chef tastes the soup and proclaims it good. the chef then turns up the stove burner and leaves.
the video pauses here to allow students to hypothesize what will happen to the soup as it heats up on the burner.
part 2
the soup in the pot gradually begins to boil; we can see steam rising from the soup.
after the soup has boiled for a while, the chef returns to the pot and tastes the soup. she or he makes a face and proclaims the soup too salty. she or he wonders what has happened.
the video pauses here to allow students to hypothesize why the soup has become too salty as it boiled, and also to predict how the chef could make the soup taste good again.
part 3:
the chef measures the soup’s volume and discovers that there is 4.5 liters of soup in the pot. rereading the recipe, the chef finds that to make the soup, she or he used five liters of water. therefore, she or he concludes that as the soup boiled on the stove, 500 ml of water evaporated into steam.
the chef concludes that if s/he adds 500 ml of water to the soup, she or he will restore the original balance of water to seasoning, and the flavor will improve.

For your initial isolation of the bacterium, you simply needed to grow enough of it that you could identify some of its more general features. thus, you used a complex nutrient agar that would allow for the growth of almost any bacterial species. different bacterial species often have very specific requirements for life. this is a fact that you can utilize when you are trying to identify the bacterium to the species level. growth conditions that will permit the growth of one species but not another may allow you to select which one you would like to culture. you can utilize different selective/differential media that allow for the growth of only one type of bacteria (e. g., either gram positive or gram negative). culturing media such as phenylethyl alcohol or sodium chloride agar will be selective/differential for gram-positive bacteria. you may also want to show that it is different from other bacteria that may be present, so you could use a selective/differential agar. selective/differential media such as blood agar or phenol red sugar broths allow for the determination of whether a bacterial cell can grow and utilize specific ingredients included in the medium and turn the agar a distinct color. sheep's blood agar utilizes red blood cells to differentiate which bacterial species may have hemolytic properties. selective or differential? 1. an agar that uses a high salt concentration to limit the growth of one type of bacteria over another would be considered selective/differential. 2. if an agar contains a dye or ph indicator in the presence of a sugar, it is generally considered selective/differential for those bacteria that may ferment the sugar over those that cannot. 3. an agar that uses the dye in crystal violet agar suppresses the growth of gram-positive bacteria. this agar would be considered selective/differential. 4. the selective/differential aspect of macconkey agar allows for the determination of which bacteria are lactose fermenters and which are not. 5. a blood agar plate contains sheep red blood cells and allows for the determination of hemolytic capabilities for all bacteria that grow on the agar. this would make this type of agar selective/differential. 6. emb agar uses lactose and two dyes that allow it to be selective/differential between the blue-black colonies of e. coli and the pinkish colonies of all other enteric bacteria. 7. bile salts in macconkey agar allow for the agar to be selective/differential for the growth of enteric gram-negative bacteria over gram-positive bacteria. 8. an agar that allows for the distinction of bacteria based on metabolism would be considered selective/differential.

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind