Contemporary Biology Chapter 1 Notes
Opening Questions:
What are the properties of life? Cells, growth and reproduction.
1.1 Properties of living things
Reproduction: All organisms reproduce their own kind.
Growth and development: Information carried by genes controls the pattern of growth in all organisms.
Energy use: Every organism takes in energy, converts it to useful forms, and expels energy.
Order: Each living thing has a complex but well-ordered structure.
Cells: All living organisms consist of cells. Some living organisms have only one cell and some have trillions of cells.
Response to the environment: All organisms respond to changes in the environment.
Evolution: Individuals with traits that help them survive and reproduce pass the genes for those traits to offspring, driving the evolution of populations.
Opening Questions:
What about a virus? Is a virus alive? No, a virus has no cells and cannot reproduce on its own.
1.2 Life can be studied at many levels
The biosphere consists of all life on Earth.
An ecosystem consists of the living and non-living components.
A community consists of all the interacting populations in an ecosystem
A population is a group of interacting individuals of one species.
An organism is an individual living being.
An organ system is a group of organs that work together.
An organ consists of multiple tissues that cooperate to perform a specific task.
A tissue is an integrated group of similar cells that work together
The cell is the fundamental unit of life.
An organelle is a component of the cell that performs a specific function.
A molecule is a group of atoms bonded together.
An atom is the fundamental unit of matter.
Opening Questions:
Does the discipline of science have any limits? The natural world
What might be an example of a limit? A limit could be outside
Is there any questions science can not answer? Ghosts as testable questions are not easy to prove with science, whether there is an afterlife, a definitive god, etc.
Observation is the first step in science. The scientific method serves as a guideline for a scientist to understand an observation.
Not all science is hypothesis driven. Discovery science provides data used to describe the natural world.
Controlled experiments investigate a hypothesis by changing only one variable.
A hypothesis is a proposed explanation for an observation. A valid hypothesis must be testable.
A theory is much broader in scope and explains a great many observations. Theories are supported by a large and growing body of evidence.
Scientists use theory with a specific meaning.
Common Language: Conjecture Speculation Opinion
Scientific Language: Well-supported Testable ideas Objective data
1.4 Cells are the fundamental units of life
Every living organism is composed of one or more cells. Some organisms are unicellular. Others are multicellular. All cells contain genes made of DNA.
All life on Earth is composed of one of two types of cells: prokaryotic or eukaryotic
Bacteria are prokaryotic cells
Prokaryotic cells are small, simple cells. They lack membrane-bound organelles.
Always unicellular First appeared 3.5 billion years ago DNA not contained Bacteria and archaea
Plants and animals have eukaryotic cells
Eukaryotic cells are larger, complex cells. They contain membrane-bound organelles.
Unicellular or multicellular First appeared 2.1 billion years ago DNA in nucleus Plants, animals, fungi, and protists
All cells contain genes—units of hereditary information—made from the molecule DNA.
Genes from one species may be cut and pasted into the DNA of a different species.
Opening Questions:
Think about the energy in the food you ate for breakfast today. Where did that energy come from? Plants and animals, atoms and cells within the animals that give the plants energy the sun. Where did that energy go? Into the energy expended when I went for a walk and when I did chores Now consider the chemicals that were in your breakfast (the atoms). Were they destroyed? no What happens to the “mass” of the food? it gets converted into human waste 🥴
The ecosystem includes all living organisms as well as non-living factors such as air, sunlight, wind, and water. The dynamics of every ecosystem depend on two main processes Energy flow and Chemical recycling
Opening Questions:
What are the differences and similarities among the following groups of organisms? A sunflower (plant) A chimpanzee (animal) A mushroom (fungi)
All three grow and use energy to grow, multicellular generally, a mushroom can be single celled though. Sunflower uses the sun for energy, a chimp uses other organisms to get energy, fungi use death to grow
Life on Earth is currently classified into three domains based on the type of cell.
Three kingdoms are recognized by how members obtain energy: Plantae (plants) Fungi Animalia (animals) Organisms that do not fit into are classified as protists.
Opening Questions:
What are some things that all living things have in common? Growth, reproduction, cells
How do living things differ from each other? How they get their energy, how they grow, the speed of growth and death and reproduction, single cell vs multicell
Evolution is the core theme of biology. All life on Earth is connected through a shared evolutionary history that stretches back over 3 billion years.
In 1859, Charles Darwin published The Origin of Species. Darwin laid out a very easy to understand logical argument for evolution by natural selection. Darwin argued that a few readily verifiable observations lead to a profound conclusion.
Every species has the potential to increase its numbers very rapidly by exponential growth. For all organisms, resources (food, shelter, sunlight) are limited.
From these two observations, Darwin concluded competition is a factor for all living things
💡 Heritable variation means that not all individuals are alike. Some individuals leave more offspring behind. Individuals with traits better suited to compete in the current environment will, on average, produce more offspring.
Darwin called the nonrandom unequal reproductive success among individuals natural selection.
Natural selection is not random because it favors individuals with traits that increase survival and reproduction.
Darwin realized that traits that enhance survival and reproduction will increase in frequency over time. Adaptation is the accumulation of favorable traits.
Darwin proposed that natural selection will result in “descent with modification.”
Life is highly diverse in the number of species. Yet there is tremendous unity among living things.
Opening Questions:
Why doesn’t penicillin work as well as it once did? Before 1940, millions of people died every year from common bacterial infections such as tonsillitis and strep throat. The discovery of antibiotics made these diseases treatable and we have come to expect protection against bacteria. However, today some of our antibiotics are no longer effective. What is going on? Come up with a hypothesis to explain the increasing incidence of antibiotic-resistant bacteria. I hypothesis that via evolution we as a species are becoming immune to antibiotics. This is seen on an individual level as we are often advised by doctors to not keep taking it as a precautionary thing as we can just be adding to our body's immunity to antibiotics as well as bacteria's evolutionary process becoming resistant to antibiotics.
You can witness examples of evolution in action all around you! Darwin noted that humans have been selecting for traits for millennia. He called this artificial selection.
💡 What are some examples of plants or animals that humans have bred for specific traits?
Antibiotics were first discovered in the 1940s. Today, some antibiotics have become virtually useless because bacteria have evolved resistance.