Download Standard 8.L.5. Molecular Biology

8.L.5 Understand the composition of various substances as it relates to their ability to serve as
a source of energy and building
materials for growth and repair of organisms.
8.L.5.1 Summarize how food provides the energy and the molecules required for building
materials, growth and survival of all
organisms (to include plants).
8.L.5.2 Explain the relationship among a healthy diet, exercise, and the general health of the
body (emphasis on the relationship between respiration and digestion).
 food provides molecules that serve as fuel and building material for all organisms. Plants
use the energy in light to make sugars out of carbon dioxide and water. This food can be
used immediately for fuel or materials or it may be stored for later use. Organisms that
eat plants break down the plant structures to produce the materials and energy they
need to survive. Then they are consumed by other.
 cells carry on the many functions needed to sustain life. They grow and divide (mitosis or
meiosis), thereby producing more cells. This requires that they take in nutrients, which
they use to provide energy for the work that cells do and to make the materials that a
cell or an organism needs. The way in which all cells function is similar in all living
organisms. Within cells many of the basic functions of organisms, such as releasing
energy from food and getting rid of waste, are carried out by different cell elements.
 matter is transferred among organisms in an ecosystem when organisms eat, or are eaten
by others for food. Matter is transferred from organisms to the physical environment
when molecules from food react with oxygen to produce carbon dioxide and water in a
process called cellular respiration. Through the process of cellular respiration, cells
convert energy (glucose) to a usable form of energy (ATP). The energy stored in ATP
provides the means by which cells are able to carry out their functions such as growth,
development, and repair of organisms, locomotion and transportation of molecules across
cell membranes.
 in plants and animals, molecules from food (a) react with oxygen to provide energy that is
needed to carry out life functions, (b) build and become incorporated into the body
structure, or (c) are stored for later use. (Also in Matter and Energy)
 matter moves within individual organisms through a series of chemical reactions in
which food is broken down and rearranged to form new molecules.
 plants use the energy from light to make sugars (food) from carbon dioxide and water.
This process transforms light energy from the sun into stored chemical energy.
 minerals and other nutrients from the soil are not food (they don’t provide energy),
but they are needed for plants to make complex molecules from the sugar they make.
 chemical energy is transferred from one organism in an ecosystem to another as the
organisms interact with each other for food.
 the atoms that make up the organisms in an ecosystem are cycled repeatedly between
the living and nonliving parts of the ecosystem. Over a long time, matter is transferred
from one organism to another repeatedly and between organisms and their physical
environment. As in all material systems, the total amount of matter remains constant,
even though its form and location change.
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energy can change from one form to another in living things. Animals get energy from
oxidizing their food, releasing some of its energy as heat. Almost all food energy comes
originally from sunlight.
A balanced diet combined with regular exercise aid in the overall general health of the
body. Humans require energy to function. The total energy can change from one form to
another in living things. Animals get energy from oxidizing their food, releasing some of
its energy as heat. Almost all food energy comes originally from sunlight.
The term food is commonly known as whatever nutrients plants and animals must take in if they
are to grow and survive. In scientific terms, food refers only to those substances, such as
carbohydrates, proteins, and lipids, from which organisms derive the energy they need to grow
and operate and the material of which they are made. It is also important to emphasize that the
sugars that plants make out of water and carbon dioxide are their only source of food. Water
and minerals dissolved in it are not sources of energy for plants or for animals.
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A balanced diet combined with regular exercise aid in the overall general health of the
body. Humans require energy to function. The total energy used by an individual depends
on the type and intensity of the activity and the energy required for basic life processes.
The amount of energy required to maintain minimum essential life functions is called basal
metabolic rate, or BMR. Humans obtain the energy required to carry out basic life
processes from the food they consume. Food energy is measured in calories. The amount
of food energy (calories) a person requires varies with body weight, age, sex, activity
level, and natural body efficiency.
For the body to use food (proteins, lipids, carbohydrates) for energy and building
materials, the food must first be digested into molecules that are absorbed and
transported to cells.
Metabolism is the set of chemical reactions involved in storing fuel (food) molecules and
converting fuel (food) molecules into energy. In order for the body to use the fuel energy
stored in food, the food must first be digested and combined with oxygen (oxidized).
Three factors contribute to the overall metabolic rate of the body. The Basal Metabolic
Rate (BMR) accounts for about 60% of all energy used by the body. Daily physical
activities such as walking and moving around account for another 30% of the energy used
by the body. Finally, 10% of the energy used by the body is used to digest and process
(oxidize) food.
If one consumes more calories than the body uses, the excess is stored and weight is
gained. Weight loss occurs when fewer calories are taken in than the body needs.
To burn food for the release of energy stored in it, oxygen must be supplied to cells, and
carbon dioxide removed. The heart /lung system work together to deliver oxygen rich
blood to all of the organs, tissues and cells of the body. Lungs take in oxygen for the
combustion of food and they eliminate the carbon dioxide produced. The circulatory
system moves all these substances to or from cells where they are needed or produced,
responding to changing demands.
In order for systems to work properly, energy from the cells must be transformed into a
useable form for cells and ultimately, organs, to perform work. These systems work
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together in order for the body to function properly and maintain a balance. Regular
exercise is important to maintain a healthy heart/lung system, good muscle tone, and
bone strength. Regular exercise and physical activity increases the heart rate providing
more oxygen for the body to use for processing food. A healthy body requires a delicate
balance between healthy diet and physical activity.
In order for energy balance to occur, Energy In = Energy Out. This means that caloric
intake equals caloric output. Food components (protein, fat, and carbohydrate) taken into
the body have the following fates: they can be used to fuel metabolic activities and
physical activities, they can be incorporated into growing body tissues, and they can be
stored as fat.
There are two important concepts of energy balance for adolescents. First, to allow for
body growth, more food energy must be consumed than can be accounted for solely on
the basis of energy required for metabolic and physical activities. Second, insufficient
energy intake may affect cellular metabolic activities, body weight, growth, tissue
formation, and health.