Evolutionary Biology Quiz

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Questions and Answers

What key evidence supports the endosymbiotic theory regarding the origins of eukaryotes?

Presence of a nucleus and linear DNA.

The ability of eukaryotes to undergo meiosis.

The cell membrane being made of phospholipids and proteins.

Mitochondria and chloroplasts having their own DNA and ribosomes. (correct)

The evolution of sexual reproduction provided a significant advantage primarily by:

Minimizing genetic changes in populations.

Ensuring rapid environmental adaptation by cloning.

Increasing the rate of cell division.

Leading to greater genetic variation in offspring. (correct)

Which of these is a characteristic feature associated with primates, and essential for depth perception?

Forward-facing eyes, for binocular vision. (correct)

A prehensile tail, for grasping branches.

A small brain size, to improve survival.

Claws, for climbing trees.

What are major advantages of bipedal locomotion in hominids?

Leaves hands free for carrying and tool use, predator avoidance, foraging, and allows better line of sight. (A) Signup and view all the answers

Based on fossil evidence, how did hominid skulls change over time?

Decreased jaw protrusion and increased brain size. (C) Signup and view all the answers

Which of the following best describes the concept of spontaneous generation?

The idea that life can emerge from nonliving materials. (D) Signup and view all the answers

What is the most widely accepted hypothesis regarding the formation of the solar system?

The Nebula Hypothesis (C) Signup and view all the answers

During the Hadean Eon, which of the following was NOT a characteristic of Earth?

An atmosphere rich in oxygen. (C) Signup and view all the answers

The Miller-Urey experiment was significant because it demonstrated which of the following?

The creation of organic molecules from inorganic compounds under early Earth conditions. (C) Signup and view all the answers

Sidney Fox's work built upon the Miller-Urey experiment. What did Fox demonstrate?

That amino acids could spontaneously form small peptides. (A) Signup and view all the answers

According to the content, what is a possibility of how amino acids could have originated?

They arrived on Earth via meteors and asteroids. (C) Signup and view all the answers

What is the main concept of the 'RNA World' hypothesis mentioned in the text?

That RNA molecules could have acted as both information carriers and catalysts. (D) Signup and view all the answers

What is the most significant contribution of cyanobacteria to the evolution of early Earth?

Initiating large-scale photosynthesis and releasing oxygen into the atmosphere. (A) Signup and view all the answers

What is a significant feature of mitochondria and chloroplasts that supports the endosymbiotic theory?

They can replicate independently of the cell. (A) Signup and view all the answers

How did sexual reproduction contribute to the evolution of complex multicellular life?

By increasing genetic variation. (C) Signup and view all the answers

Which of the following adaptations is NOT a benefit of bipedal locomotion?

Reduction in brain size for energy efficiency. (D) Signup and view all the answers

Which characteristic is true of Australopithecus as compared to Homo habilis?

Australopithecus had smaller brain sizes. (C) Signup and view all the answers

What skeletal changes were necessary for the adaptation to bipedal locomotion?

Skeletal modifications for rotating joints. (C) Signup and view all the answers

What was the primary atmosphere composition of Earth during the Hadean Eon?

Ammonia, water vapor, and methane (D) Signup and view all the answers

Which hypothesis suggests that hydrothermal vent compartments may have housed the first living cells?

Iron-sulfide Bubbles Hypothesis (B) Signup and view all the answers

What did the Miller-Urey experiment demonstrate about the origins of organic molecules?

They can arise from inorganic compounds under certain conditions (B) Signup and view all the answers

Which type of early Earth condition allowed for the cooling and formation of distinct layers?

Constant meteor impacts (C) Signup and view all the answers

What is a key feature of the RNA World Hypothesis?

Ribozymes can replicate and form proteins (A) Signup and view all the answers

What discovery was made about the meteorite found in Austria according to the Meteorite Hypothesis?

It held more than 90 amino acids, including 19 present on Earth (C) Signup and view all the answers

How did cyanobacteria contribute to the early Earth's atmosphere?

By undergoing photosynthesis and releasing oxygen (A) Signup and view all the answers

What was significant about the amino acids formed in the Sidney Fox study?

They could spontaneously form small peptides (C) Signup and view all the answers

What is the central idea behind the spontaneous generation theory?

Life arises from nonliving material. Signup and view all the answers

What were the primary gases present in Earth's first atmosphere?

Ammonia, water vapor, and methane. Signup and view all the answers

What did Sidney Fox demonstrate was possible with amino acids?

Amino acids can spontaneously form small peptides. Signup and view all the answers

What is a key characteristic of ribozymes that makes them significant in the RNA world hypothesis?

They can replicate and form proteins. Signup and view all the answers

What is the significance of the discovery about the meteorite found in Austria?

It contained more than 90 amino acids, including 19 that are found on Earth. Signup and view all the answers

What are stromatolites, and what is their importance in understanding early life?

They are structures formed by cyanobacteria; they provide fossil evidence of early colonies of life and indicate the presence of early oxygen-producing organisms. Signup and view all the answers

According to the lipid membrane hypothesis, what is the significance of liposomes?

They are spheres formed from phospholipids that may have been the first cell membranes. Signup and view all the answers

How did the development of photosynthesis by cyanobacteria alter Earth's atmosphere?

It added oxygen for the first time. Signup and view all the answers

What is the endosymbiotic theory, and which organelles are thought to have arisen through this process?

The endosymbiotic theory proposes that eukaryotes evolved when one organism lived inside another. Mitochondria and chloroplasts are thought to have arisen through this process. Signup and view all the answers

Besides the ability to walk upright, what other adaptations do mammals possess that make them successful, as described in the text?

Mammals, according to the text, also have flexible hands and feet, forward-looking eyes that allow for depth perception, have a large brain to body size, a rotating shoulder joint, and opposable thumbs. Signup and view all the answers

What is significant about Homo habilis in the context of human evolution, and how does it compare to the immediately preceding group mentioned in the text?

Homo habilis is significant because they are the first hominids known to use stone tools. Australopithecines came before Homo habilis and had smaller brains. Signup and view all the answers

How did the appearance of cyanobacteria impact the Earth's atmosphere and subsequent life forms?

Marine cyanobacteria released oxygen (O2) into the atmosphere, making aerobic respiration possible for subsequent life forms. Signup and view all the answers

What is the significance of the rotating shoulder joint and opposable thumbs for primates, including humans?

The rotating shoulder joint and opposable thumbs increased the dexterity and range of motion of primates' hands, ultimately also leading to improved ability to use tools. Signup and view all the answers

The theory of ________ explains how eukaryotes evolved through one organism living inside another.

endosymbiosis Signup and view all the answers

________, the oldest primate group, were small and nocturnal.

Prosimians Signup and view all the answers

Walking on two legs or _______, allowed hominids to have hands free for other tasks.

bipedal Signup and view all the answers

The ________ group of hominids includes those with small brains and lived 3-4 million years ago in Africa.

Australopithecines Signup and view all the answers

The species, ________, were the first to use stone tools.

H.habilis Signup and view all the answers

The hypothesis that life arises from nonliving material is called ______.

spontaneous generation Signup and view all the answers

The ______ hypothesis is the most widely accepted hypothesis for how the Earth formed.

Nebula Signup and view all the answers

The time on Earth between 4.6 and 3.8 billion years ago was called the ______ Eon.

Hadean Signup and view all the answers

The Miller-Urey experiment simulated early Earth conditions and created ______.

amino acids Signup and view all the answers

The ______ hypothesis suggests that hydrothermal sea vents provided the environment for the first living cells to form.

Iron-sulfide Bubbles Signup and view all the answers

According to the Lipid Membrane Hypothesis, ______ may have been the first cell membranes.

liposomes Signup and view all the answers

The oldest known fossils are of ______, which added oxygen to Earth’s atmosphere.

cyanobacteria Signup and view all the answers

Ribozymes in the ______ hypothesis are RNA molecules that can replicate and form proteins.

RNA World Signup and view all the answers

Study Notes

Earliest Ideas About Life's Origin

Creationism: Life arises suddenly and directly from a divine being.
Spontaneous Generation: Life arises from nonliving material. This idea posited that life could appear suddenly from nonliving things.

How the Earth Formed

Nebular Hypothesis: The most widely accepted theory. The solar system formed from a collapsing nebula of gas and dust.
Supported by Hubble Space Telescope Data: The collapsing nebula's temperature increases due to gravitational compression as it collapses; the rotation speed increases, flattening it into a disk-shape. The sun forms at the center, and dust particles outside form planetesimals, which are several kilometers across.

Early Earth Conditions

Hadean Eon (4.6-3.8 BYA): Earth was a molten planet frequently bombarded by asteroids and meteors.
Initial Atmosphere: Primarily ammonia, water vapor, methane, and other simple gases.
Oxygen Accumulation: Oxygen gradually accumulated approximately 2 billion years ago, becoming more abundant in later periods. Early earth's atmosphere lacked free oxygen.

Organic Molecule Hypotheses

Life arose gradually from inorganic molecules.
- Building blocks like amino acids combined to make more complex polymers.
Two Hypotheses:
- Miller-Urey Experiment: Simulated early Earth conditions to show that organic molecules (amino acids) could be made from inorganic compounds using energy from lightning.
- Meteorite Hypothesis: Amino acids may have arrived on Earth through meteorites or asteroids. A significant number of amino acids (90, including 19 naturally found on Earth) were found in a meteorite collected in 1969.

Further Experiments on Organic Molecule Formation

Sidney Fox (1964): Built on the Miller-Urey experiment; showed that amino acids could spontaneously form small peptides under specific conditions.

Meteorite Hypothesis (1969)

A meteorite found in Austria contained more than 90 amino acids, 19 of which occur naturally on Earth.
Possible Interpretations: Amino acids could have been present on Earth before, formed from early Earth's materials, or arrived from meteors and asteroids.

Iron-Sulfide Bubbles Hypothesis

Suggests hydrothermal sea vents produced sulfur compounds, which mixed with water to form compartments within rock. These compartments may have housed the first living cells, a`cting as a membrane-like structure.

Lipid Membrane Hypothesis

Proposed that liposomes (spheres formed from phospholipids) could have created the first cell membranes, separating the internal and external environments of early cells.

RNA World Hypothesis

Ribozymes (RNA molecules) can replicate and form proteins without the help of DNA or proteins, thus were potentially critical early in evolution.
DNA formation requires enzymes (polymerase and helicase).
RNA can be synthesized from inorganic compounds; however, DNA stores information more efficiently and is more stable.

Microbes Changed Earth's Conditions

Oldest known fossils: Cyanobacteria (3.5 BYA)
Formed Stromatolites: layered sediments trapped by cyanobacteria, providing evidence of early colonies. This process was enhanced by cyanobacteria.
Added Oxygen: Photosynthesis by cyanobacteria added oxygen to the atmosphere, causing a significant alteration in the Earth's atmosphere. This process, called oxygenation, had many important effects including making more complex life possible.

Eukaryotes Evolved by Endosymbiosis

Endosymbiosis: One organism living inside another.
Lynn Margulis (1970s): First to support Endosymbiotic Theory, explaining how mitochondria and chloroplasts evolved from prokaryotic organisms through endosymbiosis.
Evidence: Own DNA and ribosomes, circular DNA like prokaryotes, self-replication, similar size and structure to prokaryotes.

Theory of Endosymbiosis

Diagram showing the evolution from ancestral prokaryotes to eukaryotes through the infolding of the plasma membrane and subsequent engulfment, leading to the development of the nucleus and the formation of mitochondria and chloroplasts.

The Story of Life on Earth (Timeline)

Prokaryotic Anaerobic
Oldest known fossils (cyanobacteria) make oxygen.
Prokaryotic aerobic
Eukaryotic unicellular
Multicellular life

Sexual Reproduction's Impact

Genetic variation is advantageous, increasing the diversity and adaptability of a species across different environments.
Led to the evolution of complex multicellular life.

What are Primates?

Mammals with flexible hands and feet, forward-facing eyes for depth perception, and large brains relative to their body size.
Rotating shoulder joints and opposable thumbs.

Prosimians

Oldest primate group (40 million years ago).
Small and nocturnal.

Walking Upright (Bipedalism)

Bipedal locomotion required skeletal adaptations.
Advantages: Free hands for other activities, higher reach for foraging, carrying objects (infants, food, tools), predator avoidance, and protection of infants, improving both mobility and efficiency.

Fossils of Hominids

Most are either Australopithecus or Homo.
Australopithecines lived 3-4 million years ago in Africa, had small brains.
Homo genus evolved 2.4 million years ago.
Homo habilis: First stone tools, signifying an important step in human evolution.
Homo neanderthalensis: Latest extinct human group.

Changes in the Human Skull Fossils

Increased brain size in hominids over time, signifying increased cognitive ability and enhanced behavioral capabilities
Less protruding jaw. Smaller jaw in newer hominid species, indicating evolutionary changes in the skull's structure and adapting to new food sources.

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Description

Test your knowledge on key concepts in evolutionary biology, including the endosymbiotic theory, hominid evolution, and primate characteristics. Answer questions related to the major advantages of bipedal locomotion and changes in hominid skulls over time.