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

Why do humans have a third eyelid? - Dorsa Amir

Descent With Modification

The researchers placed white and brown mouse models both in abandoned fields on the mainland (dark soil) and on sand dunes on the islands (light soil) and then measured the percentage of models that were attacked by predators. What is the take-home message of the data? Do the data support or reject the hypothesis that mouse color is adaptive? <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/f2d6aec81e42ffae-1677309539293.jpg" style="width: 300px;">

Convergent Evolution in a Nutshell

Which of the following taxonomic levels contains organisms that share the most recent common ancestor?
a. family;
b. order;
c. phylum;
d. genus;
e. class

A population of snails is preyed on by birds that break the snails open on rocks, eat the soft bodies, and leave the shells. The snails occur in both striped and unstriped forms. In one area, researchers counted both live snails and broken shells. Their data are summarized below: 

Which snail form seems better adapted to this environment? Why? Predict how the frequencies of striped and unstriped snails might change in the future.<img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/0a701037b75573c8-1677716852852.jpg" style="width: 300px;">

Convergent and Divergent Evolution by Natural Selection

The drug did not work in the way that the developers intended.

No. Think about the question in relation to natural selection.

Patients did not take the drug as it was prescribed.

No. Although this may be a factor in the formation of drug-resistant pathogens, in this situation there is a better answer.

The bacterium mutated in response to the drug.

No. This is not how drug-resistant pathogens emerge.

No. One of the listed responses is correct.

Some members of the bacteria population must have had genetic variation that made them resistant to antibiotics, and these bacteria had greater reproductive success than sensitive individuals.

When does a gene for drug resistance develop in a population?

How did some strains of Staphylococcus aureus become resistant to antibiotic drugs?

Vestigial Structures

mosquitoes that survive spraying develop an immunity to the insecticide

No. This is not what would be predicted by natural selection.

mosquitoes are deliberately adapting themselves to this human-made change in the environment

the original spraying has caused a permanent mutation, giving the insects genetic resistance to the spray

No. It is far too unlikely that the spraying could lead to such an immediate advantageous mutation.

many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics

Apply what you have learned about natural selection.

When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Now, several decades later, a much smaller proportion of these insects die when sprayed. The reason fewer insects die when they are sprayed is that __________.

there's only one possible way to encode information in a macromolecule

No. That only a single system is used does not mean it is the only system that would work.

the earliest macromolecules probably arose when lightning struck an oxygen-free atmosphere

No. The question is not asking how the very first life-form may have originated.

all organisms are descended from a single common ancestor

If it works, don't fix it.

All known organisms translate genetic information to produce protein molecules via the same genetic code. This finding strongly supports the hypothesis that __________.

only the best-adapted organisms can survive

No. This does not account for similarities among dissimilar organisms.

advantageous changes can be passed along to offspring

No. Though true, this does not account for similarities among dissimilar organisms.

most evolution occurs rapidly following a mass extinction

No. Only one of the other choices is correct.

dissimilar organisms might have evolved from a distant, common ancestor

Consider what accounts for such homology.

Seemingly dissimilar organisms such as hummingbirds, humans, and whales have similar skeletal structures. This most directly suggested to biologists that __________.

Vestigial Traits and Evolutionary Misconceptions

The theory of common descent states that all modern organisms                   .
a. can change in response to environmental change;
b. descended from a single common ancestor;
c. descended from one of many ancestors that originally arose on Earth;
d. have not evolved;
e. can be arranged in a hierarchy from 'least evolved' to 'most evolved'

Traits that are derived from a common ancestor, like the bones of human arms and bird wings, are said to be                .

No. This answer is true, but there is a better response.

No. The fossils Darwin studied did show definite lines of descent, but there is a better answer.

studying adaptations of organisms to their environments

No. Darwin was especially interested in the variety of Gal&#225;pagos finch species, but there is a better answer.

the unique organisms he saw in the Gal&#225;pagos Islands

No. His interest was especially piqued by the Gal&#225;pagos finches, but there is a better response.

Which of these had a greater impact on the theory of natural selection?

During his voyage around the world, Darwin was inspired to think about evolution by __________.

Most mice living on the mainland of Florida are brown, but the mice that live on the sand dunes of the barrier islands have white fur. The differences in color are heritable, determined by genes such as MC1R. It is intuitive that the light color of beach-dwelling mice is an adaptation for blending into their environment—and thus evading predators.

What is an evolutionary adaptation?

a. a trait that improves the fitness of its bearer, compared with individuals without the trait

b. a trait that changes in response to environmental influences within the individual's lifetime

c. the ability of an individual to adjust to its environment

d. a trait that an individual wants so that it can survive

A species of crayfish that lives in caves produces eyestalks like its above-ground relatives, but has no eyes. Eyestalks in cave-dwelling crayfish are thus                   .
a. an evolutionary error;
b. a dominant mutation;
c. biogeographical evidence of evolution;
d. a vestigial trait;
e. evidence that evolutionary theory may be incorrect

an organism's traits affect only its own survival

No. An organism's heritable traits will also affect the survival of its offspring.

environmental changes have no effect on the organisms living in that environment

No. A trait that is advantageous in one environment may be detrimental in another.

natural selection operates only when an organism needs to evolve

No. Natural selection is always operating.

natural selection can improve the match between an organism and its environment

Think about how descent with modification can improve a species' chances of survival.

In Darwin's view of descent with modification, __________.

The best definition of evolutionary fitness is                   .
a. physical health;
b. the ability to attract members of the opposite sex;
c. the ability to adapt to the environment;
d. survival and reproduction relative to other members of the population
e. overall strength

Some biologists summarize evolution by natural selection with the phrase 'mutation proposes, selection disposes.' Mutation is a process that creates heritable variation. Explain what the phrase means.

Convergent vs  Divergent Evolution

What Is Adaptation? | Ecology & Environment | Biology | FuseSchool

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet?
a. maltose
b. starch
c. mannose
d. lactose

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that
a. humans and chimpanzees share a relatively recent common ancestor.
b. humans evolved from chimpanzees.
c. chimpanzees evolved from humans.
d. convergent evolution led to the DNA similarities.

Evolutionary fitness

Which of the following is not an observation or inference on which natural selection is based?
a. There is heritable variation among individuals.
b. Poorly adapted individuals never produce offspring.
c. Species produce more offspring than the environment can support.
d. Only a fraction of an individual's offspring may survive.

the passing of acquired characteristics to offspring

an individual's ability to adapt to its environment

No. Individuals do not evolve. Only populations evolve.

a way to classify organisms based on morphological similarities

No. Although Darwin's concept of evolution fit well with Linnaeus's classification system, his theory is an explanation of the pattern, not a description of it.

Darwin was thinking in terms of a process.

Darwin originally defined evolution as __________.

Summarize the key points of Darwin's theory of descent with modification, including his proposed mechanism of evolution.

Complete this concept map describing potential causes of evolutionary change within populations. 
a.
b. 
c. 
d. 
e. 
f. 
g. <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/643b7124a0839857-1677716774352.jpg" style="width: 300px;">

What type of bond is formed between two sugars in a disaccharide?
a. glycosidic linkage
b. phosphodiester bond
c. peptide bond
d. hydrogen bond

No. Lamarck is best known for proposing the inheritance of acquired characteristics.

No. Aristotle believed that all living forms could be arranged on a scale or ladder of increasing complexity, the scale of nature.

No. Wallace is best known for proposing natural selection independently of Charles Darwin.

No. Lyell is best known for uniformitarianism.

What did this person believe caused the extinctions? ?

The modern idea of extinction as a common occurrence in Earth's history was first proposed in the early-19th-century writings of __________.

No. Natural selection is differential reproductive success in nature.

No. Sexual recombination refers to new combinations of alleles resulting from fertilization.

No. Paleontology is the study of fossils.

No. Homology refers to organisms sharing traits based on common ancestry.

Consider which of these terms best implies human involvement.

The breeding of plants and animals for particular traits by humans is called __________.

Evolutionary Structures; Homologous, Analogous, and Vestigial

organisms that are positioned close to each other are closely related

No. The positioning of branch points, points at which organisms most recently shared a common ancestor, are better indications of relatedness.

scientists are sure of the correct placement and relationships of all organisms

No. Evolutionary trees are more like hypotheses for which supporting evidence is still being collected.

the concept of descent with modification is not well represented

No. The nested pattern is what would be expected from descent with modification.

homologous characteristics form a nested pattern

Think about Darwin's concept of the branching "tree of life."

On an evolutionary tree, __________.

was rejected by Darwin in favor of catastrophism

No. Darwin came to agree with Lyell that processes at work in the present could have produced observed geologic features.

was compatible with the idea of Earth being only a few thousand years old

No. For present-day earth processes to have produced observed geologic features, those processes would have had to act over millions or billions of years.

was similar to Lamarck's theory of inheritance of acquired characteristics

No. Lyell was considering geologic processes as opposed to biological processes.

states that current geologic processes are very different from those that operated in the past

No. Uniformitarianism states that current geologic processes are the same as those that operated in the past.

strongly influenced Darwin's view of how living organisms could change over time

How did this concept influence Darwin's thinking about how organisms could change given enough time?

Lyell's principle of uniformitarianism __________.

Consider the reaction between carbon dioxide and water to form carbonic acid:

CO2(g)+H2O(l)⇌CH2O3(aq)

In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate ion, as follows:

CH2O3(aq)+H+(aq)⇌CHO3−(aq)

If an underwater volcano bubbled additional CO2 into the ocean, would this sequence of reactions be driven to the left or the right? How would this affect the pH of the ocean?

Fitness, Adaptation, and Artificial Selection

Descent with Modification

An adaptation is a trait of an organism that increases                   .
a. its fitness;
b. its ability to survive and replicate;
c. in frequency in a population over many generations;
d. A and B are correct;
e. A, B, and C are correct

Define artificial selection, and compare and contrast it with natural selection.

evidence for Lamarck's theory of use and disuse

No. Lamarck's theory of use and disuse referred to body parts that would change in structure and function during an organism's lifetime.

one piece of evidence that does not support the theory of evolution

No. The presence of vestigial organs does support the theory of evolution.

examples of anatomical imperfections such as the human knee

No. This is not a term to describe anatomical imperfections.

homologies that can only be observed in embryos

No. This is not true of vestigial organs.

remnants of structures that were useful to an organism's ancestors but that are now nonfunctional or show reduced function

What is the meaning of the word vestige?

Vestigial organs are __________.

the idea that animals and plants might change over time was absent from Western science

No. Several others had at least proposed this idea.

the idea of evolution was widely accepted because it could fit into the biblical story of creation

No. Evolution is not a part of the biblical story of creation.

the idea of evolution was widely accepted by scientists, but Darwin's great impact was to popularize it for the layperson

No. Darwin proposed evolution by natural selection some time after his return from the voyage.

No. One of the other listed responses is correct.

several biologists had proposed that species might change over time, but none had suggested a convincing mechanism that might cause the change

What prevailing Earth view had Darwin grown up with?

At the time Charles Darwin sailed on HMS Beagle, __________.

Which of the following observations is not part of the theory of natural selection?
a. Populations of organisms have more offspring than will survive;
b. There is variation among individuals in a population;
c. Modern organisms are unrelated;
d. Traits can be passed on from parent to offspring;
e. Some variants in a population have a higher proba­bility of survival and reproduction than other variants do.

Which of the following observations helped Darwin shape his concept of descent with modification?
a. Species diversity declines farther from the equator.
b. Fewer species live on islands than on the nearest continents.
c. Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance.
d. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

Most mice living on the mainland of Florida are brown, but the mice that live on the sand dunes of the barrier islands have white fur. The differences in color are heritable, determined by genes such as MC1R. It is intuitive that the light color of beach-dwelling mice is an adaptation for blending into their environment—and thus evading predators.

Compare how evolution by inheritance of acquired characters and the theory of evolution by natural selection would explain the observation of white mice living primarily on light soil and brown mice living primarily on dark soil.

Darwin and Natural Selection: Crash Course History of Science #22

What are three ways monosaccharides differ from one another?

Even though marsupial mammals give birth to live young, an eggshell forms briefly early in their development. This is evidence that a.marsupials share a common ancestor with some egg-laying species;
b. marsupials are not really mammals;
c. all animals arose from a common ancestor;
d. marsupial mammals were separately created by God;
e. the fossil record of marsupial mammals is incorrect