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AST 248 - Spring 2017
Week 5 Homework Solutions
Ch 4: 8, 38, 52
Ch 5: 1, 5, 7, 8, 28, 29, 35
Chapter 4
8. The Earth is approximately 4.5 billion years old. We know this through
radiometric dating of zirconium silicate, lunar rocks, and meteorites. These
techniques showed that the Earth and the Moon had formed within 50-70
million years after the oldest meteorites were formed about 4.57 billion years
ago.
38. Earth has far less atmospheric carbon dioxide than Venus because
(c) Earth’s carbon dioxide is locked up in carbonate rocks.
52.
a. 0.1 million years = 100,000 years
0.1 million years is greater by 75,000 years
b. 0.05 billion years = 50 million years
0.05 billion years is greater by 46,000,000 million years
c. 0.1 billion years = 100 million years
0.1 billion years is greater by 99 million years
Chapter 5
1. The six key properties that appear to be shared by most living organisms on Earth are order in their internal structure, reproduction of their
own kind, growth and development in patterns determined by heredity, energy utilization to fuel activities, response to the environment or changes in
surroundings, and evolutionary adaptation to environments.
5. Carbohydrates are sugars and starches that provide energy and structure to cells. Lipids store energy for cells in the form of fats, and can also
form membranes. Proteins are molecules built from long chains of amino
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AST 248 - Spring 2017
acids which can be have a variety of functions. Nucleic acids are the hereditary material for life which allow cells to function according to specific instructions that are passed on when the cells reproduce. Enzymes are a type
of protein which serve as catalysts for biochemical reactions that take place
within cells, facilitating the reaction by accelerating it and remaining unchanged so it can be used repeatedly.
7. The three domains of life are eukarya (which includes plants, animals,
fungi, and microbes), archaea, and bacteria. Humans belong to the domain
eukarya.
8. The tree of life is is a map of the relatioships between species that is
created through the comparison of DNA in different organisms. Three main
ideas learned from the tree of life are that all large multicellular organisms
represent only three small branches of one domain (eukarya), diversity of life
on Earth is found within the microscopic ream, and the branch lengths represent the genetic differences between species, so going back toward the root
of the tree we get closer to finding a common organism for all life on Earth.
These ideas differ from the older ideas of biology that involved classifying life
into kingdoms based on visible distinctions.
28. Natural selection is the name given to (b) the mechanism by which
advantageous traits are preferentially passed on from parents to offspring.
29. Which of the following is not considered a key piece of evidence supporting a common ancestor for all life on Earth? (a) the fact that all life on
Earth is carbon-based.
35. Generally speaking, an extremophile is an organism that (a) thrives
in conditions that would be lethal to humans and other animals.
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