Biology (Holt)

CHAPTER 12Review 271

Critical Thinking

16. Recognizing RelationshipsExplain how
    multicellularity can be seen as an answer
    to the problem of a cell’s surface area-
    to-volume ratio limiting the size that
    unicellular organisms can achieve.


17. Evaluating ViewpointsSeveral scientists
    have said that if a large asteroid struck the
    Earth, the impact could result in a mass
    extinction. If an asteroid impact did not
    kill all organisms, would evolution con-
    tinue or stop? Explain.


18. Recognizing RelationshipsExplain how
    the relationship between plants and fungi
    contributed to the colonization of dry land
    by other organisms.


19. Recognizing RelationshipsAfter each of
    the five mass extinctions of Earth, there
    was a large increase of evolutionary activ-
    ity. Explain why these bursts of evolution
    occurred after the extinctions.

Alternative Assessment

20. Finding and Communicating Information
    Use the media center or Internet resources
    to learn about the conditions on Earth that
    scientists think existed before life formed.
    Identify which compounds Miller and Urey
    formed in their experiment. Prepare a report
    describing which of the compounds on early
    Earth would have contributed to the types
    of compounds Miller and Urey made.


21. Being a Team MemberWork together in
    groups to design a poster to illustrate the
    different models that describe how life’s
    chemicals may have originated. Show how
    the compounds on early Earth would have
    participated in each of these models.


22. Finding and Communicating Information
    Thomas Cech and Sidney Altman shared a
    Nobel prize in 1989 for their work on RNA.
    Research their work and the rewards asso-
    ciated with winning a Nobel prize. Relate
    your findings in an oral report.

TAKS Test PrepTAKS Test Prep

Use the diagram and your knowledge of science
to answer questions 1–3.

1.What event on early Earth is the spark

intended to simulate?

A lightning C an earthquake

B a volcanic eruption D a forest fire

2.What would the collecting chamber likely

contain if the spark were omitted from the

experiment?

F Only CH 4 , H 2 , and NH 3

GOnly H 2 O and organic compounds

HN 2 ,CH 4 ,H 2 ,NH 3 , and organic compounds

J H 2 O, N 2 , CH 4 , H 2 , and NH 3

3.What conclusion could be drawn from the

results of the experiment shown?

A Water can be changed into organic com-

pounds if it is heated vigorously.

B Organic compounds can form under

conditions like those in the experiment.

CN 2 and H 2 can be converted into NH 3

when heated.

DEarth’s early atmosphere lacked N 2.

Spark

Organic

compounds

Collecting

chamber

Condenser

H 2 O

vapor

Hot

water

N 2

CH 4

H 2

NH 3

3A

2C

7B

7B 8B

2D 3F

2D 3E

2D 3F

2C

2C

2D

Test

Allow a few minutes at the end of the test-taking

period to check for careless mistakes such as

marking two answers for a single quesiton.