AP Biology : Theorists and Evidence

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #31 : Evolution And Genetics

Scientific discoveries and advances are the result of many scientists uncovering small mysteries, each new piece of information contributing to a bigger picture. Our understanding of DNA today can be attributed to several scientists and their experiments. Which of the following scientists was able to show the diversity of DNA (and therefore the diversity of species) through patterns of base pairs?

Possible Answers:

Watson and Crick

Hershey and Chase

Darwin

Chargaff

Franklin 

Correct answer:

Chargaff

Explanation:

Chargaff was able to show the diversity of DNA through patterns within base pairs. While studying DNA, he noticed that the concentration of adenine was equal to the concentration of thymine, and the concentration of cytosine was equal to that of guanine. This led him to establish Chargaff’s rules, which state that the base composition of DNA varies between species, and for each species the percentages of adenine and thymine bases are roughly equal and the percentages of cytosine and guanine are also roughly equal.

Example Question #32 : Evolution And Genetics

Which theorist believed that the human population would grow and deplete the Earth’s limited resources?

Possible Answers:

Jean-Baptiste Lamarck

Thomas Malthus

Charles Darwin

Pierre Louis Maupertuis

Correct answer:

Thomas Malthus

Explanation:

Thomas Malthus was a political/economic theorist who observed that the human population would eventually overpopulate the world, overwhelming food and natural resources. 

Example Question #33 : Evolution And Genetics

Mitochondria and chloroplasts are believed to have evolved from __________ cells and replicate via __________

Possible Answers:

eukaryotic cells . . . mitosis

prokaryotic . . . meiosis

prokaryotic . . . binary fission

prokaryotic . . . mitosis

eukaryotic . . . binary fission

Correct answer:

prokaryotic . . . binary fission

Explanation:

Mitochondria and chloroplasts are believed to have evolved from prokaryotic cells over 1.5 million years ago. This is known as the endosymbiotic hypothesis. Mitochondria, chloroplasts, and prokaryotes all contain circular DNA and reproduce via binary fission. Mitosis involves the separation of chromosomes during the cell cycle, which is only seen in the somatic cells of eukaryotes. Meiosis is not seen in prokaryotes. 

Example Question #1 : Understanding Fossil Evidence

Which of these is an idea that Lamarck believed, but was disproven by Darwin?

Possible Answers:

Natural selection was the driving force of evolution

Closely-related individuals will share similar genetic material

Genetic drift has no impact on populations traits

Offspring could inherit acquired traits from parents 

Correct answer:

Offspring could inherit acquired traits from parents 

Explanation:

Lamarck incorrectly believed that parents could pass on traits that they had acquired to their offspring. He believed that the changes made during a lifetime, such as increased muscle mass, would be passed on to offspring. This is not true since acquired traits, except on very few rare occasions, do not affect the DNA. For example, if two parents have small muscles, but then take steroids and become bodybuilders, their offspring will still inherit the small muscle genes, since only the muscles, not the DNA is affected by bodybuilding.

Example Question #2 : Understanding Fossil Evidence

Which of these is believed to be the first type of multicellular animals?

Possible Answers:

Sponges

Arthropods

Mammals

Algae 

Correct answer:

Sponges

Explanation:

It is believed that sponges were the first animals to utilize multicellularity. Sponges only have a few cell types, including: choanocytes, porocytes, and pinacocytes. Choanocytes have flagella that beat continuously to move water, and microvilli, which are specialized for absorbing nutrients. Porocytes are tubular cells that form the pores of sponges. Pinacocytes produce collagen and provide structural support to the sponge. Although algae likely developed multicellularity early on, they are not animals. Arthropods and mammals are both multicellular and animals, but evolved after sponges.

Example Question #3 : Understanding Fossil Evidence

What is an example of information that biologists can gather from studying coprolites?

Possible Answers:

They can be studied to determine what sorts of plants or animals lived in the same time period.

They can be studied to determine an extinct animal's size.

Each of these are examples of information biologists can gather from studying coprolites.

They can be studied to determine what an extinct animal's diet consisted of.

None of these; as coprolites are not a part of the actual animal, they hold very little research value.

Correct answer:

Each of these are examples of information biologists can gather from studying coprolites.

Explanation:

Coprolites are fossilized fecal matter from an animal. By studying their contents, biologists can gather information on what the animal ate, and what species were there to be eaten by the animal.

Example Question #4 : Understanding Fossil Evidence

Scientists and paleontologists use what method in order to determine the age of an organic object?

Possible Answers:

retroactive dating

relative dating

carbon dating

Cliff face dating

index dating

Correct answer:

carbon dating

Explanation:

The key to answering this question is organic material. Once an organism dies, it ceases to participate in carbon exchanges with the atmosphere. What carbon is left in the organism then decreases at a stable rate which allows scientists to reliable date the era that the organism died in.

Example Question #5 : Understanding Fossil Evidence

Fill in the blanks with the correct answers.

The sun emits thermal neutrons that can cause __________ to deprotonate into the radioactive isotope __________.

Possible Answers:

uranium-237 . . . uranium-236

uranium-237 . . . lead-207

carbon-14 . . . carbon-13

hydrogen-1 . . . hydride

nitrogen-14 . . . carbon-14

Correct answer:

nitrogen-14 . . . carbon-14

Explanation:

When a thermal neutron collides with a nitrogen atom in the atmosphere, it causes a proton to fly off from the atom, reducing the atom from nitrogen to carbon while keeping the same number of neutrons, 14. Because the amount of matter in the universe is believed to be constant, we can measure the amount of carbon-14 left in a dead specimen to determine its age within approximately 50,000 years.

Example Question #6 : Understanding Fossil Evidence

A research team has discovered remains of a dinosaur skeleton in the field. They want to use a radiometric method to date the fossilized skeleton. Would carbon-14 dating be a useful tool in this situation?

Possible Answers:

Yes. Since the fossil is encased in rock, the carbon-14 method can be used on the rocks to determine when the fossil was buried.

No. The half-life of carbon-14 is too short to accurately date an artifact that is older than around 50,000 years, while dinosaurs lived approximately 65 million years ago.

No. Carbon-14 dating has been shown to be unreliable since the rate of decay is not constant in the environment.

Yes. Since the fossils come from an organic source, the research team can measure the remaining carbon-14 to date the fossil.

No. Dinosaur fossils contain only the carbon-13 form of the element, not carbon-14.

Correct answer:

No. The half-life of carbon-14 is too short to accurately date an artifact that is older than around 50,000 years, while dinosaurs lived approximately 65 million years ago.

Explanation:

Carbon-14 dating is used to date organic material within an approximately 50,000 year time period, due to the relatively short half life of the carbon-14 isotope. Other isotopes are used to date the rocks surrounding dinosaur fossils, such as in the uranium-lead method or the potassium-argon method.

Example Question #1 : Identify Evidence For Evolution

The wings of a bird and the wings of a beetle are considered __________.

Possible Answers:

binomial

taxonomic

phylogenetic

analogous

homologous

Correct answer:

analogous

Explanation:

Structures that are similar as a result of convergent evolution are referred to as analogous structures, such as the wings of beetles and birds. These animals do not share a common ancestor, and developed the trait for wings independent of one another. Homologous structures arise when two organisms share a trait due to linkage with a common ancestor. For example, legs of a dog and the legs of a cat are considered homologous.

Phylogeny refers to the evolutionary history of a lineage, and can be used to identify common ancestors. Taxonomy is the naming and classification of organisms. Binomial nomenclature is the scientific name for an organism containing its genus and species.

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