Characteristics of Life
What is metabolism?
The breakdown of food molecules to build energy
How does the digestive and excretory (urinary) system work together in the human body?
Digestive breaks down food, excretory excretes any waste leftover from digestion
What is the name of the variable in an experiment that remains unchanged and is used as a comparison variable?
Control Variable
What is a stimulus?
A physical factor that causes a reaction from a living organism.
What are the 4 characteristics of life?
Cells, reproduction, response to env., and a need for energy
What type of reproduction do single-celled organisms go through? Are their offspring genetically identical or different?
Asexual reproduction - genetically identical
What's the difference between positive and negative feedback loops in the human body?
Negative = counteracting response
Positive = intensifying response
A scientist believes that if given more food daily, mice will have more energy throughout the day. She gives one mouse an extra 1/4 cup of food, another 1/2 cup extra, and the third a full extra cup of food each day. One mouse receives the standard serving size of food. She measures the number of minutes they spend running on their wheel each day.
What is the independent variable of this experiment?
The varying amounts of food given to the mice.
What type of feedback loop does homeostasis follow?
Negative Feedback Loop
What is the name of the variable that is changed in the experiment?
Independent Variable
Which of the following is NOT an example of "response to the environment"? Explain why.
a. pupils dilating/constricting
b. water boiling
c. humans shivering when cold
d. humans sweating when they're hot
b. water boiling
Water is not living, the boiling of water is the change of physical state
Field mice exist with three different coat colors. White, brown, and black. Which coat color would allow for higher survival rates in a colder area where they receive lots of snowfall? Explain why.
White mice, they can hide from predators by easily blending into the snow.
A scientist believes that if given red UV rays under a lamp, then a plant will grow the tallest compared to green, yellow, and blue UV rays. He keeps one plant under normal sunlight conditions. He measures the height of the plant every 3 days. He keeps the temperature, soil type, plant type, and humidity levels the same for each plant.
What is the dependent variable?
The height of the plants.
What is the name of the variable that is measured in an experiment?
Dependent Variable
Define homeostasis.
The maintenance of constant internal conditions of a living organism.
A student observes that a plant has angled its leaves to face the sun coming through the window. Which characteristic of life BEST describes this phenomenon?
Response to environment
The alveoli in the lungs are small, thin-walled structures surrounded by many blood vessels. How does this structure support their function?
The thin walls and many blood vessels allow for oxygen gas to be inhaled and then quickly streamed into the blood for transportation.
A scientist believes that if given more food daily, mice will have more energy throughout the day. She gives one mouse an extra 1/4 cup of food, another 1/2 cup extra, and the third a full extra cup of food each day. One mouse receives the standard serving size of food. She measures the number of minutes they spend running on their wheel each day.
What is the control variable?
The mouse that receives the standard serving size of food.
Provide an example of a negative feedback loop in the human body.
Negative: glucose levels, water levels, temp., etc
Provide an example of a positive feedback loop in the human body.
Positive: blood clotting, labor contractions, etc.
When blood glucose levels rise, the pancreas releases insulin which triggers the muscle, fat and liver cells to take in extra glucose from the blood. This returns the blood glucose cells to normal levels.
In this scenario, what is the stimulus?
Elevated glucose levels
How could the circulatory and nervous system work together when humans get scared?
nervous system detects threat, sends signals to increase heart rate and respiration
A scientist believes that if dogs receive more play time with their owners, then they will have better behaviors when around other dogs. To test this, she had one dog that received no play time with their owner. She then had 3 dogs each get a set amount of playtime, one got 10 minutes a day, one got 30 minutes and the third got an hour each day with their owner. What are 3 constants the scientist should have in her experiment in order to ensure the best results?
- Same breed of dog
- Same type of play (fetch, tug of war, walking, etc.)
- Same dogs to test their behaviors
- Etc.
A scientist believes that if given red UV rays under a lamp, then a plant will grow the tallest compared to green, yellow, and blue UV rays. He keeps one plant under normal sunlight conditions. He measures the height of the plant every 3 days. He keeps the temperature, soil type, plant type, and humidity levels the same for each plant.
What is the hypothesis of this experiment?
If given red UV rays under a lamp, then a plant will grow the tallest.
What are the 4 unifying themes?
Homeostasis, systems, evolution, structure and function