1. Introduction to Biology

Natural Selection and Evolution

Imagine a situation in which a morphogen has its source at the posterior end of a Drosophila embryo. Every 100 µm from the posterior pole, the morphogen concentration decreases by half. If a cell required 1/16th the amount of morphogen found at the posterior pole to form part of a leg, how far from the posterior pole would the leg form?
a. 100 μm

b. 160 μm

c. 400 μm

d. 1600 μm

 No. The members of a given species may be spread over the world in different environments, so the same adaptations would not work for all populations. 

 No. Natural selection depends on differential reproduction, and domains do not reproduce. 

 No. A lot of evolutionary change would have to occur before new kingdoms evolved. 

Consider the emergent properties of each of these levels.

Evolution tends to act at which of the following levels?

Are already well adapted to the environment.

Reproduce sexually and live in an unstable environment.

Evolution through natural selection will occur most rapidly for populations of plants that:

Natural selection in a hurricane: The lizards that won't let go

 No. Consider which molecule determines the proteins that you would find in a cell. 

 No. Consider which molecule is responsible for the range of different lipids that would be found in a cell. 

 No. Ribosomes are collections of both RNA and protein molecules. In addition, differences between cells and between individuals are not generally due to differences in their ribosomes. 

Think about which molecule is responsible for the similarities and the differences between you and your parents.

What is the molecule that is responsible for both the unity and the diversity of life?

Charles Darwin - The Theory Of Natural Selection

Natural Selection

 No. Although chance does have a place in evolution, different traits are most often a product of natural selection. 

 No. Most shared traits arise because of descent from a common ancestor. They may also arise because of convergent evolution, but coincidence is rarely involved. 

 No. Systems biology and reductionism are ways of approaching biological problems; they are not explanations of organismal traits. 

 descent from a common ancestor; adaptation through natural selection 

Where do the unity and diversity of life come from?

With evolution as the core theme of biology, we can explain traits shared by organisms as evidence of __________ and traits that differ among organisms as evidence of __________.

It requires selective pressure from the environment.

It involves differential reproductive success.

Which of the following is true of natural selection?

Which of the following is not consistent with evolutionary theory?
a. All living organisms share a common ancestor;
b. The environment affects which organism survives to reproduce;
c. Natural selection always favors the same traits, regardless of environment;
d. Humans are not necessarily the best adapted organisms.

How Evolution Works (And How We Figured It Out)

Evolution of Antibiotic Resistance in Bacteria

Type I diabetes is a form of diabetes that is due to the loss of insulin-producing cells of the pancreas. The potential of stem cells—in particular, induced pluripotent stem (iPS) cells—for therapy has gotten a lot of press.

What are iPS cells?
a. cells taken from early human embryos

b. cells taken from the pancreas of people without diabetes

c. cells derived by de-differentiating specialized adult cells

d. cells derived by differentiating pancreas precursor cells

Type I diabetes is a form of diabetes that is due to the loss of insulin-producing cells of the pancreas. The potential of stem cells—in particular, induced pluripotent stem (iPS) cells—for therapy has gotten a lot of press.

If researchers were attempting to stimulate the differentiation of iPS cells, which of the following would they most likely add to the cell-culture medium (the liquid surrounding the cells)?
a. activin A, an extracellular signal protein
b. Sox-2, a transcription factor active in early development
c. Grb-2, an intracellular signal transduction protein
d. lactase, an enzyme that catalyzes the breakdown of lactose

What is apoptosis?
a. an experimental technique used to kill specific cells

b. programmed cell death that is required for normal development

c. a pathological condition observed only in damaged or diseased organisms

d. a developmental mechanism unique to the roundworm C. elegans

Natural Selection Animation

HHMI BioInteractive: The Origin of Species: The Making of a Theory

How inherited traits are passed from parent to offspring.

How the DNA of a population can change over time.

How evolution takes place in the natural world.

Charles Darwin’s theory of evolution by natural selection explains all of the following EXCEPT:

DARWIN'S THEORIES

Natural Selection Causes Adaptation

The Theory of Evolution (by Natural Selection) | Cornerstones Education

Adaptation Improves Fitness

 Individuals in a population of any species vary in many heritable traits. 

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

 Individuals with heritable traits best suited to the local environment will generally produce a disproportionate number of healthy, fertile offspring. 

 A population of any species has the potential to produce far more offspring than will survive to produce offspring of their own. 

 Darwin synthesized his theory of natural selection from all of the listed observations and inferences. 

Natural selection is an evolutionary process that occurs when a population's heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others.

Which of the following observations and inferences led Charles Darwin to his theory of natural selection as a mechanism for evolution?

HHMI BioInteractive: The Origin of Species: The Beak of the Finch

HHMI BioInteractive: Natural Selection & Adaptation

Evolution can Occur Via Natural Selection

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Cornerstones Education

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

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