Principles of Biology
Students work with the concepts,
principles, and theories that enable them to understand the living environment. They recognize that living organisms are made
of cells or cell products that consist of the same components as all other matter, involve the same kinds of transformations
of energy, and move using the same kinds of basic forces. Students investigate, through laboratories and fieldwork, how living
things function and how they interact with one another and their environment.
Molecules and Cells
B.1.1 Recognize that and explain how the many cells in an individual
can be very different from one another, even though they are all descended from a single cell and thus have essentially identical
genetic instructions. Understand that different parts of the genetic instructions are used in different types of cells and
are influenced by the cell’s environment and past history.
B.1.2 Explain that every cell is covered by a membrane that controls
what can enter and leave the cell. Recognize that in all but quite primitive cells, a complex network of proteins provides
organization and shape. In addition, understand that flagella and/or cilia may allow some Protista, some Monera, and some
animal cells to move.
B.1.3 Know and describe that within the cell are specialized parts for
the transport of materials, energy capture and release, protein building, waste disposal, information feedback, and movement.
In addition to these basic cellular functions common to all cells, understand that most cells in multicellular organisms perform
some special functions that others do not.
B.1.4 Understand and describe that the work of the cell is carried out
by the many different types of molecules it assembles, such as proteins, lipids, carbohydrates, and nucleic acids.
B.1.5 Demonstrate that most cells function best within a narrow range
of temperature and acidity. Note that extreme changes may harm cells, modifying the structure of their protein molecules and
therefore, some possible functions.
B.1.6 Show that a living cell is composed mainly of a small number of
chemical elements – carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulfur. Recognize that carbon can join to other
carbon atoms in chains and rings to form large and complex molecules.
B.1.7 Explain that complex interactions among the different kinds of
molecules in the cell cause distinct cycles of activities, such as growth and division. Note that cell behavior can also be
affected by molecules from other parts of the organism, such as hormones.
B.1.8 Understand and describe that all growth and development is a consequence
of an increase in cell number, cell size, and/or cell products. Explain that cellular differentiation results from gene expression
and/or environmental influence. Differentiate between mitosis and meiosis.
B.1.9 Recognize and describe that both living and nonliving things are
composed of compounds, which are themselves made up of elements joined by energy-containing bonds, such as those in ATP.
B.1.10 Recognize and explain that macromolecules such as lipids contain high energy
bonds as well.
Developmental and Organismal Biology
B.1.11 Describe that through biogenesis all organisms begin their life cycles as a
single cell and that in multicellular organisms, successive generations of embryonic cells form by cell division.
B.1.12 Compare and contrast the form and function of prokaryotic and eukaryotic cells.
B.1.13 Explain that some structures in the modern eukaryotic cell developed from early
prokaryotes, such as mitochondria, and in plants, chloroplasts.
B.1.14 Recognize and explain that communication and/or interaction are required between
cells to coordinate their diverse activities.
B.1.15 Understand and explain that, in biological systems, structure and function
must be considered together.
B.1.16 Explain how higher levels of organization result from specific complexing and
interactions of smaller units and that their maintenance requires a constant input of energy as well as new material.
B.1.17 Understand that and describe how the maintenance of a relatively stable internal
environment is required for the continuation of life and explain how stability is challenged by changing physical, chemical,
and environmental conditions, as well as the presence of disease agents.
B.1.18 Explain that the regulatory and behavioral responses of an organism to external
stimuli occur in order to maintain both short- and long-term equilibrium.
B.1.19 Recognize and describe that metabolism consists of the production, modification,
transport, and exchange of materials that are required for the maintenance of life.
B.1.20 Recognize that and describe how the human immune system is designed to protect
against microscopic organisms and foreign substances that enter from outside the body and against some cancer cells that arise
B.1.21 Understand and explain that the information passed from parents to offspring
is transmitted by means of genes which are coded in DNA molecules.
B.1.22 Understand and explain the genetic basis for Mendel’s laws of segregation
and independent assortment.
B.1.23 Understand that and describe how inserting, deleting, or substituting DNA segments
can alter a gene. Recognize that an altered gene may be passed on to every cell that develops from it, and that the resulting
features may help, harm, or have little or no effect on the offspring’s success in its environment.
B.1.24 Explain that gene mutations can be caused by such things as radiation and chemicals.
Understand that when they occur in sex cells, the mutations can be passed on to offspring; if they occur in other cells, they
can be passed on to descendant cells only.
B.1.25 Explain that gene mutation in a cell can result in uncontrolled cell division,
called cancer. Also know that exposure of cells to certain chemicals and radiation increases mutations and thus increases
the chance of cancer.
B.1.26 Demonstrate how the genetic information in DNA molecules provides instructions
for assembling protein molecules and that this is virtually the same mechanism for all life forms.
B.1.27 Explain that the similarity of human DNA sequences and the resulting similarity
in cell chemistry and anatomy identify human beings as a unique species, different from all others. Likewise, understand that
every other species has its own characteristic DNA sequence.
B.1.28 Illustrate that the sorting and recombination of genes in sexual reproduction
results in a great variety of possible gene combinations from the offspring of any two parents. Recognize that genetic variation
can occur from such processes as crossing over, jumping genes, and deletion and duplication of genes.
B.1.29 Understand that and explain how the actions of genes, patterns of inheritance,
and the reproduction of cells and organisms account for the continuity of life, and give examples of how inherited characteristics
can be observed at molecular and whole-organism levels – in structure, chemistry, or behavior.
B.1.30 Understand and explain that molecular evidence substantiates the anatomical
evidence for evolution and provides additional detail about the sequence in which various lines of descent branched off from
B.1.31 Describe how natural selection provides the following mechanism for evolution:
Some variation in heritable characteristics exists within every species, and some of these characteristics give individuals
an advantage over others in surviving and reproducing. Understand that the advantaged offspring, in turn, are more likely
than others to survive and reproduce. Also understand that the proportion of individuals in the population that have advantageous
characteristics will increase.
B.1.32 Explain how natural selection leads to organisms that are well suited for survival
in particular environments, and discuss how natural selection provides scientific explanation for the history of life on Earth
as depicted in the fossil record and in the similarities evident within the diversity of existing organisms.
B.1.33 Describe how life on Earth is thought to have begun as simple, one-celled organisms
about 4 billion years ago. Note that during the first 2 billion years, only single-cell microorganisms existed, but once cells
with nuclei developed about a billion years ago, increasingly complex multicellular organisms evolved.
B.1.34 Explain that evolution builds on what already exists, so the more variety there
is, the more there can be in the future. Recognize, however, that evolution does not necessitate long-term progress in some
B.1.35 Explain that the degree of kinship between organisms or species can be estimated
from the similarity of their DNA sequences, which often closely matches their classification based on anatomical similarities.
Know that amino acid similarities also provide clues to this kinship.
B.1.36 Trace the relationship between environmental changes and changes in the gene
pool, such as genetic drift and isolation of sub-populations.
B.1.37 Explain that the amount of life any environment can support is limited by the
available energy, water, oxygen, and minerals, and by the ability of ecosystems to recycle the residue of dead organic materials.
Recognize, therefore, that human activities and technology can change the flow and reduce the fertility of the land.
B.1.38 Understand and explain the significance of the introduction of species, such
as zebra mussels, into American waterways, and describe the consequent harm to native species and the environment in general.
B.1.39 Describe how ecosystems can be reasonably stable over hundreds or thousands
of years. Understand that if a disaster such as flood or fire occurs, the damaged ecosystem is likely to recover in stages
that eventually result in a system similar to the original one.
B.1.40 Understand and explain that like many complex systems, ecosystems tend to have
cyclic fluctuations around a state of rough equilibrium. However, also understand that ecosystems can always change with climate
changes or when one or more new species appear as a result of migration or local evolution.
B.1.41 Recognize that and describe how human beings are part of Earth’s ecosystems.
Note that human activities can, deliberately or inadvertently, alter the equilibrium in ecosystems.
B.1.42 Realize and explain that at times, the environmental conditions are such that
plants and marine organisms grow faster than decomposers can recycle them back to the environment. Understand that layers
of energy-rich organic material thus laid down have been gradually turned into great coal beds and oil pools by the pressure
of the overlying earth. Further understand that by burning these fossil fuels, people are passing most of the stored energy
back into the environment as heat and releasing large amounts of carbon dioxide.
B.1.43 Understand that and describe how organisms are influenced by a particular combination
of living and nonliving components of the environment.
B.1.44 Describe the flow of matter, nutrients, and energy within ecosystems.
B.1.45 Recognize that and describe how the physical or chemical environment may influence
the rate, extent, and nature of the way organisms develop within ecosystems.
B.1.46 Recognize and describe that a great diversity of species increases the chance
that at least some living things will survive in the face of large changes in the environment.
B.1.47 Explain, with examples, that ecology studies the varieties and interactions
of living things across space while evolution studies the varieties and interactions of living things across time.
Historical Perspectives of Biology
Students gain understanding of
how the scientific enterprise operates through examples of historical events. Through the study of these events, they understand
that new ideas are limited by the context in which they are conceived, are often rejected by the scientific establishment,
sometimes spring from unexpected findings, and grow or transform slowly through the contributions of many different investigators.
B.2.1 Explain that prior to the studies of Charles Darwin, the most widespread
belief was that all known species were created at the same time and remained unchanged throughout history. Note that some
scientists at the time believed that features an individual acquired during a lifetime could be passed on to its offspring,
and the species could thereby gradually change to fit an environment better.
B.2.2 Explain that Darwin argued that only biologically inherited characteristics
could be passed on to offspring. Note that some of these characteristics were advantageous in surviving and reproducing. Understand
that the offspring would also inherit and pass on those advantages, and over generations the aggregation of these inherited
advantages would lead to a new species.
B.2.3 Describe that the quick success of Darwin’s book Origin of Species, published in 1859, came from the clear and understandable argument it made, including the comparison
of natural selection to the selective breeding of animals in wide use at the time, and from the massive array of biological
and fossil evidence it assembled to support the argument.
B.2.4 Explain that after the publication of Origin of Species, biological evolution was supported by the rediscovery of the genetics experiments of an Austrian
monk, Gregor Mendel, by the identification of genes and how they are sorted in reproduction, and by the discovery that the
genetic code found in DNA is the same for almost all organisms.