Biology and the Tree of Life - Advanced

Question 1

What is an organism

Answer 1

An organism is a life-form - a living entity made up of one or more cells. Organisms obtain and use energy, are made up of cells, process information, replicate and evolve as populations.

Question 2

What are the five fundamental characteristics of an organism?

Answer 2

1. Energy: Organisms acquire and use energy to stay alive and reproduce (i.e. plants absorb sunlight and animals ingest food)
2. Cells: Organisms are made up of membrane-bound units called cells.
3. Information: Organisms process hereditary or genetic information, encoded in units called genes, along with information they acquire from the environment.
4. Replication: Almost everything an organism does contributes to the goal of replicating itself
5. Evolution: Organism are the products of evolution and their populations continue to evolve

Question 3

What is a theory?

Answer 3

An explanation for a general class of phenomena or observations. Most scientific theories have two components:

1. Describes a pattern in the natural world
2. Identifies a mechanism or process that is responsible for creating that pattern

Question 4

What is the cell theory?

Answer 4

All organisms are made of cells and all cells come from preexisting cells

Question 5

What is a cell?

Answer 5

A cell is defined as a highly organized compartment that is bounded by a thin, flexible structure called a plasma membrane and that contains concentrated chemicals in an aqueous solution.

Question 6

What is a hypothesis

Answer 6

A proposed explanation.

Question 7

What is the difference between a theory and a hypothesis in biology?

Answer 7

Biologists usually use the word theory to refer to proposed explanations for broad patterns in nature and prefer hypothesis to refer to explanations for more tightly focused questions.

Question 8

What is the theory of evolution?

Answer 8

The theory by Darwin and Wallace made two important claims concerning patterns that exist in the natural world:

1. Species are related by common ancestry
2. Characteristics of species cam be modified from generation to generation (descent with modification)

Question 9

What is evolution?

Answer 9

Evolution is the change in the characteristics of a population over time.

Question 10

What is natural selection?

Answer 10

If certain heritable traits lead to increased success in producing offspring, then those traits become more common in the population over time. In this way the population’s characteristics change as a result of natural selection acting on individuals.

Question 11

What is the difference between evolution and natural selection?

Answer 11

Natural selection acts on individuals

Evolutionary change occurs in populations

Question 12

What is artificial selection?

Answer 12

Changes in populations that occur when humans select certain individuals to produce the most offspring.

Question 13

How does biology define fitness?

Answer 13

Fitness means the ability of an individual to produce offspring. Individual with high fitness produce many surviving offspring.

Question 14

How does biology define adaptation?

Answer 14

In biology, adaptation is a trait that increases the fitness of an individual in a particular environment.

Question 15

What do cell theory and the theory of evolution provide as foundations of biology?

Answer 15

1. The cell is the fundamental structural unit in all organisms.
2. All species are related by common ancestry and have changed over time in response to natural selection.

Question 16

What is speciation?

Answer 16

Natural selection has caused populations of one species to diverge and form new species. The divergency process is called speciation

Question 17

What is the tree of life?

Answer 17

a family tree of organisms - a diagram that describes the genealogical relationships between species with a single ancestral species at its base

Question 18

What is the phylogeny of organisms?

Answer 18

The “tribe-source” or genealogical relationships of organisms.

Question 19

What is rRna?

Answer 19

It is a small subunit ribosomal RNA. It is an essential part of the machinery that all cells use to grow and reproduce. The rRNA molecule is made up of sequences of four smaller chemical components called riobnucleotides (A, U, C, G) that are connected linearly like boxcars on a train.

Question 20

How does rRNA sequences relate to the theory of evolution?

Answer 20

If the theory of evolution is correct, then rRNA sequences should be very similar in closely related organisms but less similar in organisms that are less closely related. Species that are part of the same evolutionary heritages, like plants, should share certain changes in rRNA that no other species have.

Question 21

What is a phylogenetic tree?

Answer 21

Just as a family tree shows relationships between individuals, a phylogenetic tree shows relationships between species. On a phylogenetic tree, branches that share a recent common ancestor represent species that are closely related. Branches that don’t share recent common ancestors represent species that are more distantly related

Question 22

What are eukaryotes? How are they different from prokaryotes?

Answer 22

Eukaryotes are cells with a nucleus and many are multicellular; however prokaryotes (including archaea and bacteria) are cells with no nucleus. The vast majority of prokaryotes are unicellular

Question 23

What are the three fundamental groups or lineages of organisms?

Answer 23

1. Bacteria
2. Archaea
3. Eukarya

Question 24

What is the scientific name of organisms?

Answer 24

These date back to 1735 when a Swedish botanist named Linneaus created a two-part name unique to each type of organism.

The first part is the genus (pl. genera) - a closely related group of species. The second part is the species. Scientific names are always italicized, with the first part being capitalized. They tend to be descriptive.

Question 25

What is the relationship between a hypothesis and a prediction?

Answer 25

Hypotheses are proposed explanations that make testable predictions. The predictions specify what we should observe if a hypothesis is correct. These predictions can be supported or rejected by collecting and analyzing data.

Question 26

What is a null hypothesis?

Answer 26

A null hypothesis specifies what we should observe when the hypothesis being tested isn’t correct.

Question 27

What are examples of correct scientific names of organisms by genus and species?

Answer 27

Saccharomyces cerevisiae (yeast)
Homo Sapiens (human)