Biology, Quarter 2, Unit 2.1
Unicellular and Multicellular Life
Overview
Number of instructional days:
10
(1 day = 50 minutes)
Content to be learned
Science processes to be integrated
•
•
Use data and observations to ask questions.
•
Analyze and interpret data (quantitative and
qualitative).
•
Use evidence to draw conclusions.
•
Communicate understanding and ideas about
interdependence and other aspects of the
natural world.
•
Use data and observation to make connections
between, to explain, or to justify what a
multicellular organism needs for survival.
Use data and observation to make connections
between, to explain, or to justify what a
unicellular organism needs for survival.
•
Explain that most multicellular organisms have
specialized cells to survive.
•
Explain that unicellular organisms perform all
survival functions and are not specialized.
•
Create and analyze models, diagrams, and/or
graphs.
•
Compare the roles of various subcellular
structures in unicellular organisms to
comparable structures in multicellular
organisms.
•
Use tools and techniques to investigate order
and organization.
•
How do specialized cells in a multicellular
organism work together to carry out life’s
functions?
•
How are various sub-cellular structures in a
unicellular organism comparable to related
structures in a multicellular organism?
Essential questions
•
What are the necessary functions of life for all
living things?
•
How does a unicellular organism carry out all
of life’s functions in only one cell?
Bristol-Warren, Little Compton, Portsmouth, Tiverton Public Schools,
in collaboration with the Charles A. Dana Center at the University of Texas at Austin
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Biology, Quarter 2, Unit 2.1
2011-2012
Unicellular and Multicellular Life (10 days)
Written Curriculum
Grade-Span Expectations
LS1 - All living organisms have identifiable structures and characteristics that allow for survival
(organisms, populations, & species).
LS1 (9-11) INQ+SAE+FAF -1
Use data and observation to make connections between, to explain, or to justify how specific cell organelles
produce/regulate what the cell needs or what a unicellular or multi-cellular organism needs for survival (e.g.,
protein synthesis, DNA replication, nerve cells).
LS1 (9-11)-1
Students demonstrate understanding of structure and function-survival requirements by…
1b explaining that most multicellular organisms have specialized cells to survive, while
unicellular organisms perform all survival functions. (e.g. nerve cells communicate with other
cells, muscle cells contract, unicellular are not specialized).
LS1 (9-11)-1
Students demonstrate understanding of differentiation by…
1c comparing the role of various sub-cellular structures in unicellular organisms to comparable
structures in multicellular organisms (e.g. oral groove, gullet, food vacuole in Paramecium
compared to digestive systems in multicellular organisms).
Clarifying the Standards
Prior Learning
In grades K–4, students were expected to cite evidence distinguishing living from nonliving things. They
identified the basic needs of plants and animals, such as water, air, food, and space. They also understood
that living things need to reproduce. They learned how the physical structures of an organism allow it to
survive in its habitat/environment.
In the grades 5–6, students recognized that different organisms have different features, such as gills or
lungs; and behaviors, such as hibernation or migration, to meet their needs for survival. They should have
been able to describe and compare how different organisms have mechanisms that work in a coordinated
way to allow them to obtain energy, grow, move, respond, defend themselves, reproduce, and maintain
internal balance. They described structures and/or behaviors that help organisms to survive in their
habitat/environment.
Beginning in grade 7, students were introduced to the cell as the basic unit of life. They understood that a
single cell has all of the same survival requirements as a “whole” organism. Students were expected to
explain relationships between or amongst the structure and function of the cells, tissues, organs, and organ
systems in an organism. They demonstrated an understanding of differentiation by identifying cells as the
building blocks of organisms. They explained that specialized cells perform specialized functions. They
should have been able to recognize and diagram the structural organization of an organism from the level
of cell to tissue, tissues to organ, organs to organ system and organ systems to organism. They compared
individual cells of tissues, and recognized similarities and the way that they work together to perform
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Bristol-Warren, Little Compton, Portsmouth, Tiverton Public Schools,
in collaboration with the Charles A. Dana Center at the University of Texas at Austin
Unicellular and Multicellular Life (10 days)
Biology, Quarter 2, Unit 2.1
2011-2012
specific functions. Students explained how each type of cell, tissue, etc. has a structure and function that
serves the organism as a whole.
Current Learning
The instructional level for this unit is developmental in terms of understanding unicellular life forms, but
reinforces the previous unit’s knowledge of subcellular structures. Students now compare and contrast
unicellular and multicellular organisms, developing an understanding of how each is able to perform all of
life’s functions.
Students use data and observation to make connections between, to explain, or to justify what a
unicellular or multicellular organism needs for survival. This could involve a study of the various needs,
such as nutrients, removal of wastes, reproduction, etc.
They then explain that most multicellular organisms have specialized cells to survive, while unicellular
organisms perform all survival functions and are not specialized. One way to approach this would be to
compare the roles of various subcellular structures in unicellular organisms to comparable structures in
multicellular organisms. For example, students could compare the way that nutrients are obtained by a
bacterium, protist, plant, fungus, and simple and complex animals.
Students use data and observations to question the role of various subcellular structures in unicellular
organisms and comparable structures in multicellular organisms in relation to survival. They should
analyze and interpret data in order to draw conclusions about the comparisons between unicellular and
multicellular life. A way to accomplish this would be through viewing and analyzing various unicellular
and multicellular life forms. This could be through the use of live specimen, prepared slides, or images.
Students should be expected to evaluate differences and similarities amongst these organisms.
Student should communicate understanding and ideas by creating and/or analyzing models, using
diagrams and/or graphs, or participating in discussion of these ideas. This unit lends itself very well to the
use of tools and techniques of biologists (i.e., microscopy, slide preparation, etc.).
Students compare and contrast the structures and functions of various unicellular and multicellular
organisms. They could use microscopes, models, diagrams, or images to accomplish this. Within
multicellular organisms, the students consider different types of specialized cells and how this
specialization provides for their function. Additionally, they recognize the interdependence of these
different cell types, which work in a coordinated way that allows for survival.
In a classroom, students might be found researching and then presenting information about various ways
in which unicellular and multicellular organisms accomplish the same function of life. For example, waste
removal as carried out by a bacterium, protist, plant, fungus, simple and complex animal.
In this unit, students explore unicellular life for possibly the first time. In earlier grades, they had a clear
understanding that living things have needs, however most of their experience was limited to plants and
animals. Although they previously studied the structures and functions of the cell, they were not
considering the cell as an independent living thing with all of the same needs as a multicellular organism.
Students are now expected to make the connections between subcellular structures in a unicellular
organism and related structures in a multicellular organism. Additionally, they now explore the
interdependence of specialized cells in multicellular organisms, which will help bridge to the next unit:
homeostasis.
Bristol-Warren, Little Compton, Portsmouth, Tiverton Public Schools,
in collaboration with the Charles A. Dana Center at the University of Texas at Austin
C-15
Biology, Quarter 2, Unit 2.1
2011-2012
Unicellular and Multicellular Life (10 days)
Future Learning
The next unit of study is homeostasis, which will require knowledge of the interdependence of specialized
cells in a multicellular organism. It will also require an understanding that unicellular organisms have the
same basic survival needs as a multicellular organism, including homeostasis.
This exploration of diversity (unicellular to multicellular) sets the stage for their later investigation of
evolution and classification.
Additional Findings
Among 16-year-old students, there is some confusion about levels of organization. Responses suggest that
pupils thought that molecules of protein are bigger than the size of a cell and that single-celled organisms
contain intestines and lungs. The pupils in the study had been taught about cells in the previous year and
superficially ‘knew’ a number of correct statements about them. However, over a third of responses
revealed ‘inadequate’ alternative ideas about cells (Making Sense of Secondary Science, p. 25).
In a study of children aged 5–16, researchers found that almost all children recognized animal examples
as living; 70–80 percent of 12- to 15-year-olds regarded a particular plant as living. Almost all the
children attributed growth to plants, but apparently did consider this a prerequisite of life (Making Sense,
p. 19)
The familiar description and depiction of cells in blood sometimes lead students to the notion that
organisms contain cells rather than that organisms are mostly made up of cells. Imagining the large
number of cells is also a problem for young students. Large organisms are composed of about a trillion
cells, but this number means little to middle school students. Students may have even more difficulty with
the idea that cells are the basic unit in which life processes occur. Neither familiarity with functions of
regular-sized organisms nor observations of single-celled organisms will reveal much about the chemical
activities going on inside single cells (Benchmarks for Science Literacy, p. 110).
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Bristol-Warren, Little Compton, Portsmouth, Tiverton Public Schools,
in collaboration with the Charles A. Dana Center at the University of Texas at Austin