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Questions and Answers
What are the five fundamental characteristics of all living organisms?
What are the five fundamental characteristics of all living organisms?
What is meant by the term 'cell theory'?
What is meant by the term 'cell theory'?
Cell theory states that all living organisms are composed of cells and that all cells arise from pre-existing cells.
The 'cell theory' was challenged by the concept of 'spontaneous generation'.
The 'cell theory' was challenged by the concept of 'spontaneous generation'.
True (A)
Louis Pasteur’s experiments disproved the theory of spontaneous generation.
Louis Pasteur’s experiments disproved the theory of spontaneous generation.
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Why is the replication of cells crucial for life to exist?
Why is the replication of cells crucial for life to exist?
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What is the central dogma of molecular biology?
What is the central dogma of molecular biology?
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What are the four building blocks that make up each strand of DNA?
What are the four building blocks that make up each strand of DNA?
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The two strands of DNA are held together by hydrogen bonds between pairs of bases.
The two strands of DNA are held together by hydrogen bonds between pairs of bases.
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DNA is directly involved in synthesizing proteins in a cell.
DNA is directly involved in synthesizing proteins in a cell.
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What is the role of proteins in a cell?
What is the role of proteins in a cell?
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Which of the following processes require energy?
Which of the following processes require energy?
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What is the fundamental purpose of acquiring energy for organisms?
What is the fundamental purpose of acquiring energy for organisms?
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Organisms acquire energy only in the form of adenosine triphosphate (ATP).
Organisms acquire energy only in the form of adenosine triphosphate (ATP).
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What is evolution?
What is evolution?
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What are the two main claims made by Darwin and Wallace regarding the natural world?
What are the two main claims made by Darwin and Wallace regarding the natural world?
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Explain what is meant by 'descent with modification'.
Explain what is meant by 'descent with modification'.
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Natural selection acts on populations, not individuals.
Natural selection acts on populations, not individuals.
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Speciation is the formation of a new species from an existing species.
Speciation is the formation of a new species from an existing species.
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What is a phylogenetic tree?
What is a phylogenetic tree?
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Branches on a phylogenetic tree that share a recent common ancestor indicate a closer evolutionary relationship between the species.
Branches on a phylogenetic tree that share a recent common ancestor indicate a closer evolutionary relationship between the species.
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The 'tree of life' is based solely on physical characteristics of organisms.
The 'tree of life' is based solely on physical characteristics of organisms.
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How can biologists use RNA and DNA sequences to determine evolutionary relationships?
How can biologists use RNA and DNA sequences to determine evolutionary relationships?
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What are the three major groups of organisms, as indicated by the 'tree of life'?
What are the three major groups of organisms, as indicated by the 'tree of life'?
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All organisms within the domain of Bacteria are single-celled.
All organisms within the domain of Bacteria are single-celled.
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Organisms within the domain of Eukarya can be either single-celled or multicellular.
Organisms within the domain of Eukarya can be either single-celled or multicellular.
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What are the four essential components of the scientific method?
What are the four essential components of the scientific method?
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The purpose of a control group in an experiment is to isolate the effect of the variable being tested.
The purpose of a control group in an experiment is to isolate the effect of the variable being tested.
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Study Notes
Biological Science Course Introduction
- Biology is the study of life
- Living organisms share five fundamental characteristics:
- Cells: All organisms are made of membrane-bound cells
- Replication: All organisms can reproduce
- Information: Organisms process hereditary information (genes) and environmental information
- Energy: Organisms acquire and use energy
- Evolution: Populations of organisms evolve over time
Theories
- Theory: A general explanation for a class of phenomena supported by evidence
- Differs from everyday use (e.g., a "guess") in science
- Cell Theory: Explains the composition of organisms
- Theory of Evolution by Natural Selection: Explains the origins of organisms
- Chromosome Theory of Inheritance: Explains the transmission of hereditary information
Life is Cellular and Replicates through Cell Division
- 1665: Robert Hooke used a microscope to discover and name cells
- Observed small compartments in cork
- 1600s: Anton van Leeuwenhoek built microscopes with greater magnification
- Observed single-celled organisms ("animalcules")
- 1800s: Cell theory developed:
- All organisms are made of cells
- All cells come from preexisting cells
All Organisms are Made up of Cells
- Cells are highly organized compartments separated from their environment by a membrane barrier.
- The first part of the cell theory was the understanding that all organisms are made up of cells
- All cells come from pre-existing cells.
Terminology
- Theory: Explains broad patterns
- Hypothesis: A testable statement explaining an observation
- Experiment: Allows researchers to test the effect of a factor on a phenomenon
- Prediction: Measurable or observable result that must be correct if the hypothesis is valid
Cell Theory vs Spontaneous Generation
- Cell theory challenged spontaneous generation
- All-cells-from-cells is a hypothesis
- Cells grow and divide to produce new cells
- Spontaneous generation: The belief that organisms can arise spontaneously under certain conditions
The Spontaneous Generation and All-Cells-From-Cells Hypotheses Were Tested Experimentally by Louis Pasteur
- Pasteur's experiment demonstrated that cells arise from cells and not from spontaneous generation
- Straight-necked flasks: Cells appeared due exposure to air, resulting in the growth of microbes.
- Swan-necked flasks: Cells did not appear due to the filter-like curve in the flask, preventing microbes from entering the flasks.
Life Replicates Through Cell Division
- Cells must replicate for life to exist
- All cells in multicellular organisms descend from previously existing cells
How is Hereditary Information Encoded and Passed During Cell Division?
- Chromosomal theory of inheritance:
- Hereditary information is encoded in genes
- Genes are located on chromosomes
- DNA is the hereditary material
- DNA is made of deoxyribonucleic acid molecules
- Genes are segments of DNA coding for cell products
DNA is a Double Helix
- Rosalind Franklin, James Watson, and Francis Crick proposed that DNA is a double-stranded helix
- DNA is made of four building blocks: A, T, C, and G
- The sequence of these blocks (A, T, C, G) carries information for an organism's growth, development, and reproduction
- DNA strands are bonded based on specific pairings:
- A pairs with T
- C pairs with G
The Central Dogma Describes the Flow of Genetic Information
- DNA codes for RNA which codes for proteins
- RNA (ribonucleic acid) carries out specialized functions in cells
- Messenger RNA (mRNA) translates DNA code into protein production
- Proteins are crucial for carrying out cell tasks; forming structural components and promoting chemical reactions
DNA is Copied to Pass Genetic Information
- Copying DNA is accurate
- DNA changes (mutations) could lead to changes in proteins
- DNA changes lead to heritable variations and diversity
Life Requires Energy
- Organisms have two fundamental nutritional needs:
- Acquiring chemical energy (ATP)
- Obtaining molecules for building blocks (DNA, RNA, proteins)
- How organisms get energy is key to diversification of life
Life Evolves
- Evolution is the change in characteristics of a population over time, reflecting relatedness of species by common ancestry.
- Modifications from generation to generation are called descent with modification
Evolution and Natural Selection
- Evolution: Change in characteristics of a population over time where species arise from a common ancestor
- Population: Group of individuals of the same species
- Natural Selection: Explains evolution in that individuals vary in heritable characteristics; certain versions help individuals reproduce more than others.
Natural Selection and Evolutionary Change
- Certain heritable traits lead to increased success in producing offspring; these traits become more common over time
- Natural selection acts on individuals
- Evolutionary change occurs in populations
- Speciation occurs when populations diverge to form new species
The Phylogenetic Tree of Life
- Phylogenetic tree: Used to show relationships between species
- Branches that share a recent common ancestor represent species closely related; those further apart are more distantly related
- Data for the tree is often determined from genetic data.
How is Genetic Variation Analyzed?
- Biologists study RNA and DNA sequences from different organisms to compare building blocks (A, T, C, G)
- Fewer variations indicate closer evolutionary relationships.
The Tree of Life Was Produced by Comparing Genetic Sequence Data
- Three major groups of organisms are shown in the tree (Domains): Eukaryotes (have a nucleus), Bacteria, and Archaea (both prokaryotes, lack a nucleus).
Doing Biology
- Science is based on asking questions that can be answered by collecting and analyzing data.
- Formulating a hypothesis is important
- Use of a control group helps in isolating the effect of the factor under investigation
- Experimental conditions and large sample size are crucial for valid findings.
How Do Foraging Desert Ants Navigate?
- Desert ants meander to find food, then return to the nest in a straight line
- The question is how do they find their way back?
Pedometer Hypothesis for How Ants Navigate
- Pedometer hypothesis: Ants track steps taken and stride length to know their distance from the nest.
- Null hypothesis: Stride length and number of steps have no effect on how the ant finds its way back to the nest; another mechanism is used for navigation.
Experimental Setup
- Ants were divided into three groups: stumps (shorter leg length), normal, and stilts (longer leg length) to understand whether stride length affects navigation
Do Desert Ants Use a "Pedometer"?
- Experiments were conducted as a test of the pedometer hypothesis.
- Data was collected to see if the manipulation of leg length affect their ability to find their nest.
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Description
This quiz introduces key concepts in biology, including the characteristics that define living organisms and various scientific theories that explain biological phenomena. Topics such as Cell Theory, Theory of Evolution, and the significance of cellular structure and replication are covered. Test your understanding of how life is defined and studied.
