1. Introduction to Biology

2. Chemistry

3. Water

4. Biomolecules

5. Cell Components

6. The Membrane

7. Energy and Metabolism

8. Respiration

9. Photosynthesis

10. Cell Signaling

11. Cell Division

12. Meiosis

13. Mendelian Genetics

14. DNA Synthesis

15. Gene Expression

16. Regulation of Expression

17. Viruses

18. Biotechnology

19. Genomics

20. Development

21. Evolution by Natural Selection

22. Evolution of Populations

23. Speciation

24. History of Life on Earth

25. Phylogeny

26. Prokaryotes

27. Protists

28. Plants

29. Fungi

30. Overview of Animals

31. Invertebrates

32. Vertebrates

33. Plant Anatomy

34. Vascular Plant Transport

35. Soil

36. Plant Reproduction

37. Plant Sensation and Response

38. Animal Form and Function

39. Digestive System

40. Circulatory System

41. Immune System

42. Osmoregulation and Excretion

43. Endocrine System

44. Animal Reproduction

45. Nervous System

46. Sensory Systems

47. Muscle Systems

48. Ecology

49. Animal Behavior

50. Population Ecology

51. Community Ecology

52. Ecosystems

53. Conservation Biology

[BOOK BIO] CLUTCH

Surface Area, Volume, Diffusion and Osmosis

Surface Area to Volume Ratio

Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allows species to exploit more resources and frees them from the need to hide in small refuges.

Which of the following might be a trade-off of gigantism experienced by giant island tortoises?
a. They cool very rapidly during cold weather.
b. It would be difficult to sustain their high mass-specific metabolic rates on a diet of plants alone.
c. It could be more difficult to avoid thermally unfavorable conditions.
d. They could hide from nonnative predators more easily.

Homeostatic Control Systems - Homeostatic Control Mechanisms and Feedback Control Loops

Metabolism and Homeostasis

Homeostasis - negative and positive feedback (thermoregulation and lactation)

Which of these examples best describes the concept that form facilitates function?
a. Crickets must balance their resources between spermatophore production and immune defenses.
b. A desert jackrabbit has large ears that help eliminate excess heat.
c. An Antarctic fish maintains homeostasis by conforming to the stable, external temperature.
d. Honeybees will swarm around a predatory wasp and contract their flight muscles to generate a lethal ball of heat.

All the cells in the body have much the same chemical composition.

No. The similarity of chemical composition results from the chemical requirements for life.

DNA stores the genetic information in a cell.

No. This simply describes the function of DNA.

All organs are composed of the same four kinds of tissue.

No. Although this is a true statement, homeostasis is a concept of physiology, not anatomy.

The lung has a large surface for exchange of gases.

No. This is an example of a structural-functional relationship.

Elevated blood CO2 stimulates faster breathing, which rids the body of excess CO2.

Consider that "homeo-" means "same," and "-stasis" means "standing still."

Which of the following best illustrates homeostasis?

Surface area to volume ratio  why cells are small

Higher Biology - 2.3 Metabolic Rate

True or False: The increase in red blood cell count in tourists visiting Tibet is an example of acclimatization.

Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allows species to exploit more resources and frees them from the need to hide in small refuges.

Which tortoises, mainland or island, need to eat more food per gram of their body mass?

The signal is broadcast throughout the body.

No. Signals of the nervous system typically target a specific cell or cells.

Signals travel slowly, often taking many seconds to have an effect.

No. This is true about the action of hormones; nerve impulses move very quickly.

No. This is true about the action of hormones; nerve impulses have a very short duration.

Signals generally coordinate gradual changes that affect the entire body.

No. This is true about the action of hormones.

Communication usually involves more than one type of signal.

Consider the ways that hormones work.

Which of the following is a characteristic of the nervous system but not the endocrine system?

They are chemical signals broadcast throughout the body.

No. Although this is true, is this the only correct response?

They act only on cells with receptors specific to that hormone.

They are relatively slow acting compared to nerve impulses.

Consider the properties of hormones that distinguish their actions from the actions of nerves.

Which of the following statements is/are true of hormones?

Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allows species to exploit more resources and frees them from the need to hide in small refuges.

On a trip to the Galápagos Islands, you overhear a group of tourists refer to tortoises as 'cold blooded.' Explain why this word is not accurate to describe a giant tortoise.

Feedback Regulation

Examine the experimental chamber in Figure 6.8a. Explain what would occur by osmosis if you added a 1-M solution of sodium chloride on the left side and an equal volume of a 1.5 M solution of potassium ions on the right. How might the addition of the CFTR protein to the lipid bilayer impact the direction of water movement? <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/d40291c2e02f1330-1677292681046.jpg" style="width: 300px;">

Surface Area, Volume, and Life

The eukaryotic cytoskeleton is a highly dynamic network of filaments and motor proteins. Which of the following correctly describe activities of these cytoskeletal components? Select True or False for each statement.
T/F Myosin motors walk toward the plus ends of intermediate filaments.
T/F Dynein motors are responsible for the whip-like movement of eukaryotic flagella.
T/F Kinesin motors move vesicles along tracks toward the microtubule-organizing center.
T/F Actin filaments are required for cytoplasmic streaming.

free-living unicellular organisms are difficult for predatory organisms to detect and capture

No. Though it may be true that smaller organisms are more likely to be undetected by predators, this is a result of their small size, not the reason for it.

many more cells can be packed into an organ while maintaining its compact size

No. It would be more efficient to produce an organ from a smaller number of large cells than from many small cells.

smaller cells require fewer nutrients and increase the probability of survival

No. Although this may be true, it is not the fundamental reason why cells are small.

the amount of vulnerable plasma membrane is minimized relative to that of a larger cell with more cytoplasm

No. Just the opposite is true. Volume increases at a faster rate than surface area.

the ratio of surface area to cell volume is maximized

Consider the ways that size and shape influence the physical properties of cells.

Most cells are microscopic because at this small size, __________.

Homeostasis - What Is Homeostasis - What Is Set Point For Homeostasis- Homeostasis In The Human Body

Surface Area to Volume Ratio Explained

What are three attributes of mitochondria and chloroplasts that suggest they were once free-living bacteria?

Consider the energy budgets for a human, an elephant, a penguin, a mouse, and a snake. The            would have the highest total annual energy expenditure, and the            would have the highest energy expenditure per unit mass.
a. elephant; mouse
b. elephant; human
c. mouse; snake
d. penguin; mouse

Metabolic Rate - What Is Metabolic Rate - Basal Metabolic Rate - How Many Calories Burned In A Day

Homeostasis

Cell Surface Area: Volume Ratio | Cell Biology

Suppose a cell is placed in a solution with a high concentration of potassium and no sodium. How would the cellular sodium–potassium pump function in this environment?
a. It would stop moving ions across the membrane.
b. It would continue using ATP to pump sodium out of the cell and potassium into the cell.
c. It would move sodium and potassium ions across the membrane, but no ATP would be used.
d. It would reverse the direction of sodium and potassium ions to move them against their gradients.

Surface Area to Volume Ratio of the Cell

Homeostasis and Negative/Positive Feedback

enzymatic hydrolysis; DNA and RNA; more cells

No. Although it is true that food is digested by enzymatic hydrolysis, what is absorbed and what is generated are not correct.

No. Although it is true that nutrients are absorbed, how food is digested and what is generated are not correct.

No. . Although it is true that nutrients are absorbed, how food is digested and what is generated are not correct.

No. Although it is true that nutrients are absorbed and ATP is generated, acids are not the way that food is digested.

Consider all of the reasons that you need to eat food.

In most animals, food is digested by __________, __________ are absorbed by body cells, and most energy-containing molecules are used to generate __________.

Homeostasis Video 3:  Feedback Loops

George Palade's research group used the pulse–chase assay to elucidate the secretory pathway in pancreatic cells. If they had instead performed this assay on muscle cells, where would you expect the labeled proteins to end up during the chase? (Muscle cells consist primarily of actin and myosin filaments and have high energy demands for muscle contraction.)

No. Of the organisms listed here, dogs are not the smallest endotherms. In general, larger endotherms require fewer calories per kilogram of body weight than smaller endotherms.

No. Humans are large endotherms. In general, larger endotherms require fewer calories per kilogram of body weight than smaller endotherms.

No. Very large endotherms have high total energy requirements, but they require less food per kilogram of body weight than smaller endotherms.

No. Sheep are large endotherms. In general, larger endotherms require fewer calories per kilogram of body weight than smaller endotherms.

Consider the relationship between metabolic rate and size.

Which of the following animals would you expect to consume food at the highest rate (kilograms of food per kilogram of body weight per day)?

An animal's inputs of energy and materials would exceed its outputs
a. if the animal is an endotherm, which must always take in more energy because of its high metabolic rate.
b. if it is actively foraging for food.
c. if it is growing and increasing its mass.
d. never; due to homeostasis, these energy and material budgets always balance.

Positive and Negative Feedback loops and homeostasis

Which of the following cell structures would you expect to be most important in the growth of bacteria on the surface of your teeth?
a. cell wall
b. fimbriae
c. flagella
d. cilia

Your sweat glands secrete sweat and your blood vessels dilate after receptors detect an increase in your core body temperature.

No. This is an example of negative feedback, not a cyclical event occurring over the course of 24 hours.

Your body produces more red blood cells at higher elevations.

No. This is an example of acclimatization, adjusting to your current environment.

Injured blood vessels release chemicals to attract platelets to initiate the clotting process. The process is amplified by the secretion of more platelet-attracting chemicals from the existing platelets.

No. This is an example of positive feedback, wherein the body amplifies a stimulus (in this case, the platelet-attracting chemicals).

Your body temperature rises and falls every day.

Circadian rhythms reflect physiological changes over a set period of time.

Which of the following is a function of your circadian rhythm?

No. The nervous system does help control the body, but the circulatory system is not directly involved in coordination and control.

No. The endocrine system does help control the body, but the immune system is not directly involved in coordination and control.

No. These systems work together, but they are not directly involved in coordination and control.

These systems use nerve impulses and hormones.

The __________ system and the __________ system work together to coordinate and control physiological processes in most animals.

Which of the following animals uses the largest percentage of its energy budget for homeostatic regulation?
a. marine jelly (an invertebrate)
b. snake in a temperate forest
c. desert insect
d. desert bird

Describe ways in which the bodies of complex animals are structured for exchanging materials with the environment. Do all animals share such features?

Negative-feedback mechanisms are 
a. most often involved in maintaining homeostasis. 
b. analogous to a furnace that produces heat. 
c. found only in birds and mammals. 
d. all of the above

While driving your car over hilly terrain, you maintain a constant speed of 55 miles per hour. Write a short paragraph describing how this illustrates the concept of homeostasis.

No. Although it also involves a decrease in body temperature and heart rate, hibernation is an example of long-term torpor.

No. Thermoregulation is the maintenance of a relatively constant internal temperature.

No. Acclimatization is an adjustment to current environmental conditions.

No. Thermogenesis is the production of heat.

What is happening to the dormouse and with what frequency?

During the night, the dormouse forages and eats, but during the day, its body temperature and heart rate drop significantly. This is an example of what physiological process?

Metabolism & Nutrition, Part 1: Crash Course Anatomy & Physiology #36

Homeostasis | How Your Body Keeps the Balance!

No. The standard metabolic rate is a measurement of the energy expenditure of an ectotherm.

No. The metabolic rate is the sum of the energy expended over any given time period. The correct answer is more specific.

No. Bioenergetics refers to the overall flow of energy within an organism.

No. An organism's energy budget is a comparative measure of its energy intake versus its energy expenditure.

What is the minimum metabolic rate of a nongrowing endotherm?

The amount of energy expended while an endothermic organism is resting, unstressed, and not actively digesting or growing is called its __________.

Metabolic Rate

Compared with a smaller cell, a larger cell of the same shape has
a. less surface area.
b. less surface area per unit of volume.
c. the same surface-area-to-volume ratio.
d. a smaller cytoplasm-to-nucleus ratio.

The cells of an ant and an elephant are, on average, the same small size; an elephant just has more of them. What is the main advantage of small cell size? (Explain your reasoning.)
a. A small cell has a larger plasma membrane surface area than does a large cell.
b. Small cells can better take up sufficient nutrients and oxygen to service their cell volume.
c. It takes less energy to make an organism out of small cells.
d. Small cells require less oxygen than do large cells.

Which of the following best illustrates homeostasis? (Explain your answer.)
Most adult humans are between 5 and 6 feet tall.
All the cells of the body are about the same size.
When the salt concentration of the blood goes up, the kidneys expel more salt.
When oxygen in the blood decreases, you feel dizzy.

Basal Metabolic Rate (BMR) || Basal Metabolic Rate Biochemistry

Water Balance Homeostasis

Energy Considerations in Nutrition: BMR, RMR & Physical Activity – Nutrition | Lecturio

Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allows species to exploit more resources and frees them from the need to hide in small refuges.

The graph shown here compares the average carapace (shell) length of mainland and island tortoises. Summarize the results, then use the data to predict whether the surface area to volume ratio is higher in mainland or island tortoises. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/e5ec52d3b04feca2-sar.jpg" alt="" /><img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/639a45352a8f31cf-1677301586297.jpg" style="width: 300px;">

Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allows species to exploit more resources and frees them from the need to hide in small refuges.

True or false: The body temperatures of island tortoises always closely match the temperatures in their environments.

Human Physiology - Homeostasis & Feedback Loops

Homeostasis Video 4:  Physiological Feedback Loops

Maintaining Homeostasis Nervous and Endocrine

DRAW IT Draw a model of the control circuit(s) required for driving an automobile at a fairly constant speed over a hilly road. Indicate each feature that represents a sensor, stimulus, or response.

positive; improving the operating conditions in the jogger's body

No. The body is acting to decrease CO2 levels.

positive; decreasing the CO2 concentration

No. Positive feedback acts to increase deviation from the set point or normal range. If this were a positive feedback system, the result would be a continued increase in the jogger's rate of CO2 production.

positive; restoring the CO2 concentration to the set point

No. The body is acting to decrease CO2 levels; positive feedback would act to continue the increase in the jogger's rate of CO2 production.

negative; acting in opposition to one another

No. The circulatory and respiratory systems are working together to decrease CO2 levels.

negative; acting to oppose the increase of CO2 from the set point or normal range

Consider whether the body is acting to increase or decrease the intensity of the initial stimulus.

When a jogger starts to run, the rate at which his muscles produce CO2 rises sharply. But the CO2 in his blood rises only slightly before he starts to breathe faster and his heart starts beating stronger. Soon his increased rate of CO2 production is balanced by an increased rate of CO2 removal. This would be an example of __________ feedback because the jogger's circulatory and respiratory systems are __________.

Negative because it accentuates fluctuations and keeps the system from reaching equilibrium

No. Positive feedback acts to increase the intensity of the initial stimulus.

Positive because it keeps systems constant despite fluctuations in the external environment

No. Positive feedback acts to increase the intensity of the initial stimulus; it is negative feedback that maintains homeostasis.

Positive because it magnifies deviations from the "set point"

Negative because it tends to keep a system at a desirable set point or normal range

Think of the two types of feedback.

What kind of feedback most directly maintains homeostasis? Why is this?

Which of the following statements regarding surface area and volume in animals are correct? Select True or False for each statement.
T/F As an animal grows, its volume increases more rapidly than its surface area.
T/F A chihuahua has a higher surface area to volume ratio than a great dane.
T/F Animals with high surface area to volume ratios heat and cool more slowly than animals with lower surface area to volume ratios.
T/F As an animal's volume increases, its total surface area decreases.