The universal genetic language of DNA is common to virtually all organisms on Earth, however diverse. What is the best explanation for this fact?
a) All living things share a common genetic language of DNA because they share a common ancestry.
b)The universal nature of the genetic language of DNA is due to coincidence.
c)The universal genetic language is explained by the chemistry of DNA and proteins.
Definition
a)All living things share a common genetic language of DNA because they share a common ancestry.
The genetic code is arbitrary, at least to some extent. The fact that all organisms share a single genetic code is due to their common ancestry. Read about the core theme of biology: Evolution accounts for the unity and diversity of life.
Term
What is the correct order for the hierarchy of biological organization from the least to the most complex?
Each level of biological structure builds on the level before it.
Term
Which of the following statements is not true of scientific experiments?
a)They must occur under carefully controlled conditions found in a laboratory.
b)They must be well documented.
c)They yield useful results regardless of whether the hypothesis is supported or rejected.
Definition
a)They must occur under carefully controlled conditions found in a laboratory.
Not all experiments are performed under laboratory conditions; many occur outdoors in uncontrolled conditions. Scientists must account for these variations when designing experiments.
Term
In an experiment, investigators try to control all of the variables except one—the one that tests the hypothesis. Which of the following reasons is the primary rationale for controlling variables in an experiment?
a)To create a control group
b)To eliminate alternative explanations for the results of an experiment
c)To enable investigators to repeat the test
Definition
b)To eliminate alternative explanations for the results of an experiment
Controlling all variables but one ensures that some other factor is not responsible for the results obtained from an experiment.
Term
Which of the following variables did Pasteur change in his experiment to test the hypothesis of spontaneous generation?
a)The length of time that the broth was boiled
b)The length of time that the flasks were allowed to sit before being sampled for organisms
c)The shape of the flask
d)The broth used in each flask
Definition
c)The shape of the flask
By using a swan-necked flask for the experimental treatment, Pasteur ensured that no cells were entering the flask from the air. Thus, any organisms that appeared in the experimental flask would have arisen spontaneously.
Term
In Pasteur's experiment to test the hypothesis of spontaneous generation, why did he boil the broth in both flasks?
a)To attract dust particles to each flask
b)To kill any existing organisms in the broth
c)To expose the broth to a source of organisms
d)To provide nutrients to stimulate the growth of microorganisms
Definition
b)To kill any existing organisms in the broth
Pasteur boiled the broth to kill any existing organisms, thus ensuring that the conditions in each flask were identical (i.e., lacking organisms) at the start of the experiment.
Term
Select the correct statement about the process of scientific inquiry.
a)The goal of scientific research is to prove the stated hypothesis.
b)It is possible to test hypotheses, such as those involving historical events, without conducting experiments.
c)If the results of an experiment do not support the hypothesis that is tested, the experiment is badly designed.
Definition
b)It is possible to test hypotheses, such as those involving historical events, without conducting experiments.
Although it is not possible to carry out experiments to test hypotheses about evolutionary relationships between living groups or about the timing of the origin of major evolutionary innovations, such hypotheses can be evaluated by making predictions about the expected findings that would result from these hypotheses. Data can then be collected to test whether these predictions are correct. Read about the forms of scientific inquiry and the scientific method.
Term
Competition is central to the theory of natural selection. Why does competition occur?
[image]
Definition
b)Organisms typically produce too many offspring, and resources are limited.
Resource competition is one of the main ingredients for natural selection. Organisms must compete for limited resources, and only the best adapted will survive and reproduce.
