SvS Biology
2001:
Charlotte's Web it's not!
Maintaining a Balance (module 9.2)
According to the Board of Studies Syllabus, the purpose and function for studying this unit is summarised by the following statements:
(ref: NSW Board of Studies Stage 6 Syllabus, page 43)
Contextual Outline
Multicellular organisms have specialised organ systems that are adapted for the uptake and transport of essential nutrients from the environment, the utilisation or production of energy and the removal of waste products arising from cellular activities.
The basis of healthy body functioning in all organisms is the health of their cells. The physical and chemical factors of the environment surrounding these cells must remain within narrow limits for cells to survive. These narrow limits need to be maintained and any deviation from these limits must be quickly corrected. A breakdown in the maintenance of this balance causes problems for the organism. The nervous and endocrine systems in animals and the hormone system in plants bring about the coordinated functioning of these organ systems. They are able to monitor and provide the feedback necessary to maintain a constant internal environment. Enzyme action is a prime example of the need for this balance. Enzymes control all of the chemical reactions that constitute the body’s metabolism.
As enzymes normally function only within a narrow temperature range, even a small rise in body temperature can result in the failure of many of the reactions of metabolism that are essential to life.
The following is the syllabus document created by the BOARD OF STUDIES. It shows the requirements of each component of the course.
All underlined text represents suggested links to information or activities that you should be familiar with and use as a starting point in gaining a knowledge and understanding of this topic.
1. Most organisms are active in a limited temperature range
Theory:
• identify the role of enzymes in
metabolism, describe their
chemical composition and use a
simple model to describe their
specificity on substrates
• identify the pH as a way of
describing the acidity of a
substance
• describe the effect of the following
on enzyme activity:
– increased temperature
– change in pH
– change in substrate
concentrations
• explain why the maintenance of a
constant internal environment is
important for optimal metabolic
efficiency
• describe homeostasis as the
process by which organisms
maintain a relatively stable internal
environment
• explain that homeostasis consists
of two stages:
– detecting changes from the
stable state
– counteracting changes from the
stable state
• outline the role of the nervous system in detecting and responding to environmental
changes using temperature change as an example
• outline the role of a feedback mechanism in maintaining a stable body temperature
• identify receptors and responses used by humans to maintain a stable internal temperature across a
range of environmental conditions
• identify the broad range of temperatures over which life is found compared with the narrow
limits for individual species
• distinguish between the terms ectotherm and endotherm, naming Australian examples
• describe responses of Australian ectothermic and endothermic organisms to changes in the
ambient temperature and explain how these responses assist temperature
regulation
• identify some responses of plants to temperature change
Practical:
• identify data sources, plan, choose equipment or resources and perform a first-hand investigation
to demonstrate the effect of:
– increased temperature
– change in pH
– change in substrate concentrations on the activity of a named enzyme
• gather, process and analyse information from secondary sources and use available
evidence to develop a model of a feedback mechanism
• gather, process and analyse information from secondary sources to distinguish between
ectotherms and endotherms, name Australian examples and use available evidence to describe
adaptations or responses of these organisms that assist temperature regulation
2. Plants and animals transport dissolved nutrients and gases in a watery medium
Theory:
• identify the form(s) in which each of the following is carried in
mammalian blood:
– carbon dioxide
– oxygen
– water
– salts
– lipids
– nitrogenous waste
– other products of digestion
• explain the adaptive advantage of haemoglobin and discuss the
physiological responses of
mammals to decreased oxygen
concentrations experienced at high
altitudes
• compare the structure of arteries, capillaries and veins in relation to
their function
• describe the main changes in the
chemical composition of the blood
as it moves around the body and
identify tissues in which these
changes occur
• outline the need for oxygen in living cells and explain why
removal of carbon dioxide from
cells is essential
• outline the body’s response to
increased carbon dioxide concentration in the blood as an
example of maintaining the
balance in blood composition
concentrations
• describe current theories about processes responsible for the
movement of materials through
plants in xylem and phloem tissue
Practical:
• identify data sources, plan, choose equipment or resources and
perform a first-hand investigation
to demonstrate the effect of
dissolved carbon dioxide on the
pH of water
• perform a first-hand investigation using the light microscope and
prepared slides to gather information to
estimate the size of red and white blood cells and draw
scaled diagrams of each
• gather, process and analyse information from secondary
sources to identify current
technologies that allow measurement of oxygen saturation
and carbon dioxide concentrations
in blood and describe and explain
the conditions under which these
technologies are used
• gather, process and analyse information from secondary
sources to identify and describe
the products extracted from
donated blood and the uses of
these products
• gather, process, analyse and present information from
secondary sources to report on
progress in the production of
artificial blood and use available
evidence to propose reasons why
such research is needed
• choose equipment or resources to
perform a first-hand investigation
to gather first-hand data to draw
transverse and longitudinal
sections of phloem and xylem
tissue
• gather, process, analyse and present information from
secondary sources to compare the
movement of materials through
mammals and flowering plants
3. Plants and animals regulate the concentration of gases, water and waste products of metabolism in cells and in interstitial fluid
Theory:
• recall the role of the respiratory and excretory systems in
maintaining humans as functioning
organisms •
identify the role of water as a solvent for metabolic reactions in
living cells and explain why the
concentration of water in cells
must be held constant
• explain why the removal of wastes is essential for continued
metabolic activity
• compare the waste products of a range of terrestrial and aquatic
organisms and explain why these
differences occur
• identify the role of the kidney in
the excretory system of fish and
mammals
• explain why the processes of diffusion and osmosis are
inadequate in removing dissolved
nitrogenous wastes
• distinguish between active and passive transport and relate these
to processes occurring in the
mammalian kidney
• explain how the processes of filtration and reabsorption in the
mammalian nephron regulate body
fluid composition
• outline the role of the hormones, aldosterone and ADH
(vasopressin), in the regulation of
water and salt levels in blood
• define enantiostasis as the maintenance of metabolic and
physiological functions in response
to variations in the environment
and discuss its importance to
estuarine organisms in maintaining
appropriate salt concentrations
• describe adaptations of a range of
terrestrial Australian plants that
assist in minimising water loss
Practical:
• perform a first-hand investigation
of the structure of a mammalian
kidney by dissection, use of a
model or visual resource and
identify the regions involved in the
excretion of waste products
• gather, process and analyse
information from secondary
sources to compare the process of
renal dialysis with the function of
the kidney
• gather, process, analyse and
present information to outline the
general use of hormone
replacement therapy in people
who cannot secrete aldosterone
and use available evidence to
discuss the importance of this
therapy
• perform a first-hand investigation
to gather information about
structures in plants that assist in
the conservation of water
• gather, process and analyse
information from secondary
sources to compare and explain
the differences in urine
concentration of terrestrial
mammals, marine fish and
freshwater fish
• process and analyse information
from secondary sources and use
available evidence to explain the
relationship between the
conservation of water and the
production and excretion of
concentrated nitrogenous
wastes in a range of Australian insects
and terrestrial mammals
• process and analyse information from secondary sources and use
available evidence to discuss
processes used by different plants
for salt regulation in saline
environments
• process and analyse information from secondary sources and use
available evidence to assess the
impact of urban development on
the health of aquatic organisms
inhabiting these waterways
Outcomes
This module contributes to the following HSC course outcomes:
H4 assesses the impacts of applications of biology on society and the
environment
H5 identifies possible future directions of biological research
H6 explains why the biochemical processes associated with cell organelles are
related to macroscopic changes in the organism
H11 justifies the appropriateness of a particular investigation plan
H12 evaluates ways in which accuracy and reliability could be improved in
investigations
H13 uses terminology and reporting styles appropriately and successfully to
communicate information and understanding
H14 assesses the validity of conclusions from gathered data and information
H15 explains why an investigation is best undertaken individually or by a
team
H16 justifies positive values about and attitudes towards both the living
and non-living
components of the environment, ethical behaviour and a desire for critical
evaluation of the consequences of the applications of science.
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S. van Strien