Transcript UNIT I: MATTER AND ENERGY

Science classwork # 1:
Classify the following changes as physical or chemical
changes. Give evidence for your answer. Say if there are
both physical and chemical changes:
a. Water falling over a waterfall
b. Lava from a solidifying volcano
c. A plane taking off
d. Iron nails moving due to the presence of a magnet
e. Food going bad after a few days
When we see that there is an increase in the
temperature of a material system, is it always a sign
that there has been a chemical change? Explain and
give an example to back up your answer.
Science classwork # 2:
Open your books and read pages 46 and 47. Then solve
the activities on the right side of page 47.
Nutrition: Is the process
through which organisms
obtain the substances
they need; like water,
food and oxygen. To be
precise, there are two
things that we obtain
from nutrition: matter
and energy.
Part of the food we eat is transformed into matter, which
later adds to our bodies; the other part of the food is
transformed into energy to carry out the vital functions
we already know about.
Although there
are processes we
do not notice,
that doesn’t
mean that they
do not require
energy. Even
when we’re
sitting down,
resting or
sleeping we use
energy.
 Producers (plants): These
organisms only take inorganic
substances from the
environment like oxygen,
carbon dioxide, mineral salts
and water. They also need an
external source of energy to
carry out their nutrition.
 Consumers (animals): They
also take inorganic
substances, but they need
organic substances (food),
too. These organisms obtain
energy from food.
Producer nutrition
 Plants use their roots to absorb water and mineral salts
and make up a substance called crude sap.
 Crude sap is transported to the leaves where the plant
cells take the sunlight to carry out photosynthesis (the
manufacture of organic substances).
 Organic substances are mixed with the water from the
sap to make up a new substance known as elaborated
sap, which circulates throughout the whole plant.
 Chemosynthesis is the other way to manufacture
organic substances, which is done by certain bacteria
using the chemical reactions in the environment as the
external energy source, instead of using sunlight.
Consumer nutrition
 Consumers can’t create bio-molecules from inorganic
substances like plants, so they must manufacture them
from organic substances.
 According to what they eat, consumers may be:
herbivores, carnivores or omnivores.
 Consumers obtain energy with the digestive process:
First, breaking up the food they consume to transform
it into a substance that can be absorbed by the cells.
Then, cells obtain the energy and manufacture biomolecules by means of chemical reactions.
 The digestive process is carried out by four systems:
the digestive system; the respiratory system; the
circulatory system and the excretory system.
 Draw a picture (or pictures) presenting examples of
how food transforms into matter and energy.
 Why do we say that we’re always using energy? Explain
and give an example.
 Explain the difference between producer and
consumer organisms.
As we already
studied at the
beginning of this
unit, the nutritional
process is carried out
by a complex system
which includes four
different organ
systems.
The digestive system
It is formed by the digestive tract and associated glands.
Its main function is to process foods in order to extract
water, sugars, fats and proteins from it.
This system is divided in three parts
 Digestive: Occurs in the mouth, the stomach and the
small intestine. It separates the substances that can be
used from the food.
 Absorption: Occurs in the small intestine. The
substances that can be used pass into the bloodstream.
 Expulsion: Occurs in the large intestine. Undigested
remains and unusable substances are expelled.
The respiratory system
 It is formed by the respiratory paths and the lungs. The
respiratory movements are produced constantly and
allow air to enter and leave the lungs.
 One of the substances organisms obtain during the
nutritional process is oxygen, and it can only be done
with the help of the respiratory system.
The circulatory system
It is formed by the heart and
the blood vessels. This
system circulates the blood
through the whole body.
Food substances, water and
oxygen are transported from
the digestive system to the
cells.
The excretory system
 It is formed by the kidneys and
the urinary tracts. This system
eliminates waste substances in
the blood which may be toxic.
The kidneys filter the blood and
separate all these substances
which are expelled in the urine.
 The sweat glands also
participate in this process by
producing sweat.
 Explain how the digestive, circulatory, respiratory and
excretory systems participate in the nutritional process
of consumer organisms.
 Explain the difference between photosynthesis and
chemosynthesis.
 Which process is consumer organisms can be
considered their equivalent to chemosynthesis?
As we can easily see, food goes bad and gets rotten
sooner or later. However, this is a natural process which
happens due to the existence of micro-organisms in the
environment and the food itself.
These micro-organisms are:
 The fungi that grow in food are responsible for the
appearance of mould. You might have seen an orange
or a piece of bread with mould on it. This is a fungus
that grows on the food and means it is useless for
consumption.
 Bacteria are everywhere. Many of them are responsible
for food rotting. Rotting is a natural transformation
and degradation process of proteins through the
action of bacteria. This process produces bad-smelling
substances which warn us that the food has been
altered.
Preserving food at home
The oldest ways of preservation are drying, salting and
smoking; however, the most common are feezing and
refrigerating foods:
 Drying is one of the most ancient food preservation
techniques, which reduces water activity sufficiently to
prevent or delay bacterial growth.
 Salting draws moisture from the meat through a
process of osmosis. Meat is cured with salt or sugar, or
a combination of the two.
 Smoking is the process of flavoring, cooking, or
preserving food by exposing it to the smoke from
burning plant materials, most often wood. Meats and
fish are the most common smoked foods, though
cheeses, vegetables, and ingredients used to make
beverages such as whisky, are also smoked.
 Refrigeration preserves food by slowing down the
growth and reproduction of micro-organisms and the
action of enzymes which cause food to rot. The
introduction of refrigerators improved the diets of
many by allowing foods to be stored safely for longer
periods, particularly during warm weathers.
 Freezing is one of the most commonly used processes
for preserving a very wide range of food including
prepared food stuffs which would not have required
freezing in their unprepared state. For example, potato
waffles must be kept in the freezer, but potatoes
themselves require only a cool dark place. In domestic
freezers the temperature is around 10 degrees below
zero. At this level the action of micro-organisms is
stopped almost completely.
Industrial ways of preservation
All traditional ways of preservation are also used in
industry; but these processes are not apt for all kinds of
foods, like milk, a substance that should be consumed
inmediatelly.
As a result of this, industry has developed more
sofisticated ways of preserving foods:
 Food additives are substances added to food to
preserve flavor, enhance its taste and make it last
longer, like with preservatives. Some additives have
been used for centuries; for example, preserving food
by pickling (with vinegar) or using sulfur dioxide as in
some wines.
 Sterilization techniques are used in the food industry
to eliminate all the micro-organisms. There are
different ways of sterilization, being pasteurization the
most widely-used. This technique, mostly applied to
milk, consists of heating it at 80 degrees for 30
seconds. This process kills 99.5% of all the germs
contained in milk.
Illnesses of the digestive system
 Ulcers: An ulcer is small wound that appears on the
stomach walls. This illness is normally related to stress
and it causes severe pain when food is ingested.
 Gastritis: An inflammation of the stomach walls,
which causes a burning sensation and makes digestion
difficult.
 Gastroenteritis: It is due to infections caused by
viruses, bacteria or food poisoning. It causes
discomfort, pain, fever, vomiting and diarrhea.
 Cavities: The progressive destruction of teeth caused
by the bacteria which live in the mouth.
Illnesses of the respiratory system
Besides the “common cold” bronchitis and asthma are
the most common.
 Bronchitis: An inflammation of the bronchia caused
by a bacterium. An antibiotic treatment is required.
 Asthma: An allergic reaction which causes sudden
muscular contractions of the bronchioles, making
breathing particularly difficult.
Illnesses of the circulatory system
Normally, due to the obstruction of the blood vessels as a
result of bad nutritional habits, alcohol and stress.
 Arteriosclerosis: A serious illness caused by the
accumulation of fats in the arteries.
 Thrombosis: Due to the forming of blood clots. The
clot circulates until it reaches a narrow blood vessel,
where it gets stuck.
 Heart attacks or angina: Severe conditions caused by
the obstruction of the coronary arteries which take the
blood to the cardiac muscles.
Illnesses of the excretory system
They mostly affect the urinary tract, the kidneys and the
bladder; some of them may become very serious if not
treated properly and on time.
 Kidney infection: Characterized by the presence of
blood in the urine and backache.
 Kidney stones: Caused by the accumulation of renal
calcium in the kidney. It is very painful.
1. Interaction
 We may define interaction as the capacity that
organisms and systems have of making contact,
interacting and communicating with their
environments, habitats or other organisms and
systems.
 Interaction among organisms is diverse, for it includes
a variety of actions such as looking for and finding
food, protection from danger or courting the females
of the species.
We may also say that interaction refers to a sequence of
complex actions divided in three steps:
 Obtain information from the external or internal
environment (Done with the organs of sense).
 Process information that is received and decide on a
response. This only occurs in animals. (Done by the
nervous system).
 Respond to the information that is received. (Done by
the responsive organs like muscles, bones and
tendons).
The information that an organism receives is called “the
stimulus, which provokes a response. When this
response involves movement, we may classify it into two
different types:
 Positive responses: The organism responds by moving
towards the stimulus.
 Negative responses: The organism responds by moving
away from the stimulus.
In the case of plants, the functions on interaction and
co-ordination are different because they do not have a
nervous system. However, plats do receive stimuli and
respond.