Biology: How Life Works Chapter 1

Biology

The science of how life works.

Biologists

Scientists who study life.

Observation

The act of noticing and describing events or processes in a careful, orderly way.

Experimentation

A disciplined and controlled way of asking and answering questions about the world in an unbiased manner.

Hypothesis

A tentative explanation for one or more observations that makes predictions that can be tested by experiments or additional observations.

Variable

The feature of an experiment that is changed by the experimenter from one treatment to the next.

Test group

The experimental group that is exposed to the variable in an experiment.

Control group

The group that is not exposed to a variable in an experiment.

Scientific method

A deliberate, careful, and unbiased way of learning about the natural world.

Theory

A general explanation of the world supported by a large body of experiments and observations.

4 key characteristics of living organisms

1. complexity, with precise spatial organization on several scales

2. the ability to change in response to the environment

3. the ability to reproduce

4. the capacity to evolve

First Law of Thermodynamics

Energy can neither be created nor destroyed; it can only be transformed from one form into another.

Second Law of Thermodynamics

The number of possible positions and motions of molecules in the universe tends to increase.

Entropy

A quantitative measure of disorder or randomness, symbolized by S.

Cell

Basic unit of life

Deoxyribonucleic Acid (DNA)

Double-stranded nucleic acid found in the nucleus which provides instruction for making proteins; provides hereditary information

Protein

The key structural and functional molecule that do the work of the cell.

Ribonucleic Acid

(RNA) single-stranded nucleic acid that contains the sugar ribose

Transcription

The synthesis of RNA from a DNA template. Copying of one form to the other.

Translation

Converts information stored in the language of nucleic acids to information in the language of the proteins.

Central Dogma

DNA -> RNA -> Protein

States that information flows in one direction from DNA to RNA to proteins.

Gene

A segment of DNA on a chromosome that codes for a specific trait or protein product.

Replicated

Copied

Mutations

Random errors in gene replication that lead to a change in the sequence of nucleotides. The source of all genetic diversity.

Plasma Membrane

the organelle that controls what enters and leaves the cell

Nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Prokaryotes

No nucleus

Eukaryotes

Have nucleus

Three domains of life:

Bacteria

Archaea

Eukarya

Metabolism

The chemical reactions by which cells convert energy from one form to another and build and break down molecules.

Adenosine Triphosphate (ATP)

main energy source that cells use for most of their work

Evolution

change over time

Natural Selection

A natural process resulting in the evolution of organisms best adapted to the environment.

Environmental Variation

Differences between organisms caused by environmental factors.

Genetic Variation

Differences among individuals in the composition of their genes or other DNA segments

Ecology

The study of how living things interact with each other and their environment.

In some experiments, several identical groups are set up, keeping conditions similar among them. In the _____ group, a change is deliberately introduced. In the _____ group, this change is not introduced. In this way, the researcher can determine if the change has an effect.

test; control

The study of how organisms interact with each other and with their physical environment in nature is called:

ecology

A major difference between eukaryotic cells and prokaryotic cells is that:

eukaryotic cells have a nucleus and prokaryotic cells do not.

Imagine walking through a tropical rainforest. You notice that there are different types of trees, birds, insects, and other organisms. A few weeks later you are taking a walk through the desert and notice that the trees, birds, insects, and other organisms are different than those you saw in the rainforest. Which of the following statements BEST explains the differences between each of these ecological systems?

Organisms in each ecological system have evolved in that system and have adaptations suited for that environment.

All of the answer options are ways humans are affecting life on Earth.

Humans have affected life on Earth in which of the following ways?

We have altered or destroyed the habitat of many species.

All of the answer options are ways humans are affecting life on Earth.

Many species have been driven to extinction.

Some species have actually benefited from human activities.

We are contributing to the carbon, nitrogen, and other biogeochemical cycles.

All organisms use which of the following molecules to carry out metabolic reactions?

ATP

Which of the following sequences correctly represents the scientific approach to learning?

observation → question → hypothesis → experiment

Translation is the process by which:

proteins are synthesized from RNA molecules.

The feature of an experiment that is changed from one treatment to the next is referred to as a(n):

variable

Measuring its costs and benefits in terms of energy spent and/or gained, mutualism:

results in gain for both individuals.

Observations allow scientists to draw tentative explanations called hypotheses.

True

When small molecules are linked together to form larger molecules, the increase in entropy typically comes from:

heat.

_____ is NOT a domain of life.

Protists

According to the phylogenetic tree shown in Figure 1.16, the primate MOST closely related to humans is the:

Chimpanzee.

Ecological relationships reflect the _____ traits of organisms in nature.

behavioral, physiological, and biomechanical

Which one of the following statements about the human impact on Earth's ecology is CORRECT?

Agriculture has increased abundance and distribution of some species, while decreasing abundance and distribution of other species.

Humans commandeer as much as 25 percent of all photosynthetic production on land.

More atmospheric nitrogen is converted to ammonia by humans than by the rest of nature.

Human activities produce more carbon dioxide than do volcanoes.

All of these statements about the human impact on Earth's ecology are correct.

All of these statements about the human impact on Earth's ecology are correct.

Imagine that you are standing in a field and you see a group of butterflies. You notice an individual that looks significantly different from the other butterflies in the population. This difference allows the butterfly to escape predation more efficiently than other butterflies in the population. How might this trait have arisen in the individual?

There was a random mutation in a gene that led to differences in the ability to escape predation.

Which of the following is an example of the first law of thermodynamics in action?

Light energy is transformed into chemical energy during photosynthesis.