Transcript Previously… - JohnTanScienceEportfolio

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Photosynthesis is…
• The process by which plants use carbon
dioxide, water and light trapped by
chlorophyll to make food in the form of
glucose, with oxygen being given off during
the process.
+
+
Photosynthesis
• The process in word equation…
Carbon
+ Water
dioxide
Light
chlorophyll
Glucose
+
Oxygen
Conditions essential for
photosynthesis
Sunlight (light energy)
Light energy is converted to
chemical energy stored in
glucose.
Chlorophyll
This green pigment absorbs light
energy and changes it into
chemical energy needed to
manufacture glucose.
Suitable temperature
Photosynthesis depends on the reactions
of enzymes in the chloroplasts. Enzyme reactions
are fastest at a suitable temperature.
Carbon dioxide and water
These are the raw materials needed to
form carbohydrates (glucose).
glucose
water
Importance of photosynthesis
• Why is photosynthesis important?
- Photosynthesis makes chemical energy
available to animals
- Photosynthesis removes carbon dioxide and
provides oxygen.
Photosynthesis makes chemical
energy available to animals
• All living organisms need energy to move, grow,
excrete, reproduce and maintain themselves.
Video: energy
Photosynthesis makes chemical
energy available to animals
• What is the ultimate source of energy for animals?
Light energy from the Sun.
• During photosynthesis, light energy is absorbed by
chlorophyll and transformed into chemical energy.
Light
energy
chlorophyll
chemical
energy
Cellular Respiration
• Chemical energy is locked up in food molecules such as
glucose.
• The chemical energy stored in food molecules is released
to living organisms in a process called cellular
respiration.
Chemical Energy
(in food)
Cellular respiration
Energy
(for organisms)
Cellular Respiration
• Cellular respiration takes place in all the living cells of
organisms
• Since living cells need energy to carry out many vital
processes all the time, respiration occurs all the time.
Cellular Respiration
Cellular
Respiration
Main Focus
Aerobic
Respiration
Tissue
Respiration
Anaerobic
Respiration
External
Respiration
Aerobic Respiration
• Aerobic respiration is the process whereby food
substances are broken down in the presence of oxygen
with the release of energy in living cells. Carbon dioxide
and water are released as waste products.
• Word equation for aerobic respiration:
Glucose + Oxygen
Video: res in cells
Carbon +
Water + Energy
dioxide
Tissue Respiration
• Tissue respiration is the process by which food
substances are broken down in living cells.
• A large amount of energy is released for the cells to
perform different activities.
• In tissue respiration, glucose combines with oxygen to
release energy, carbon dioxide and water.
Glucose + Oxygen
Carbon +
Water + Energy
dioxide
External Respiration
• External respiration is the process of bringing the oxygen
from the surrounding environment to the cells for tissue
respiration to take place.
• External respiration is also responsible for removing from
the body the carbon dioxide and water formed during
tissue respiration.
• Breathing is part of external respiration.
Importance of Aerobic Respiration
• Most organisms respire aerobically. Energy released is
used for:
- Growth (building up of proteins)
- Muscle contractions (e.g. heartbeats)
- Digestion and absorption of food substances
- Cell division
Aerobic Respiration
• Do plants carry out aerobic
respiration in the day?
Yes. Plants carry our aerobic
respiration all the time.
Aerobic Respiration in Plants
During the day, plants photosynthesise. The oxygen
produced is more than what is needed for aerobic
respiration. The excess oxygen is released to the
surroundings.
At night, photosynthesis stops. Plants take in oxygen
from the surroundings for aerobic respiration and give
off carbon dioxide to the surroundings.
Video: plant
Aerobic Respiration
• Oxygen is taken in from the surrounding air
while carbon dioxide and water are released to
the surroundings.
• In plants, these respiratory gases (oxygen,
carbon dioxide & water) are exchanged with
the surroundings through the stomata.
• In humans, the respiratory gases are
exchanged with the surroundings using the
respiratory system.
Human Respiratory System
Video: Airway
Human Respiratory System
• Components of the human respiratory system
- nose
- nasal cavity
- pharynx
- trachea
- bronchus
- bronchioles
- alveoli
- diaphragm
- lungs
Human Respiratory System
• Components of the human respiratory system
- nose
- nasal cavity
- pharynx
- trachea
- bronchus
- bronchioles
- alveoli
- diaphragm
- lungs
In the nose…
• Air enters through two
external nostrils. The nostrils
lead into two nasal passages
which are lined with a moist
mucous membrane.
In the nose…
Passing the air through the
nasal cavity has the
following advantages:
1.
dust and foreign particles
are trapped by the hairs in
the nostrils and by the
mucus on the mucous
membrane.
2.
air is moistened and
warmed before it enters the
lungs.
From the nose to the trachea
The air in your nasal
passages enters the
pharynx. From the pharynx,
air passes into your larynx
and then into your trachea.
The trachea and bronchi
The lower end of the trachea
divides into two
tubes/bronchi. Each bronchus
(plural: bronchi) connects to
one lung.
The trachea and bronchi
• Each bronchus divides
continually and ends in
bronchioles. Each
bronchiole ends in a
cluster of air sacs or
alveoli (singular:
alveolus).
bronchioles
alveoli
The trachea and bronchi
• Thousands of alveoli are
found in lungs, and these
alveoli provide a very
large surface area for
gaseous exchange.
• Gaseous exchange is
possible because alveoli
are well-supplied with
blood capillaries.
Video: Gas exchange between the lungs and blood
bronchioles
alveoli
The trachea and bronchi
• Wall of alveolus is one
cell thick → faster rate of
diffusion of gases through
it
• Thin film of moisture
covers surface of alveolus bronchioles
→ allows oxygen to
alveoli
dissolve in it
Breathing
• The physical process by which respiratory gases are
exchanged with the surroundings.
• It is also the movement that brings air into and out of the
body.
Breathing
• Inhalation / Inspiration - taking in of air from the
surroundings
Breathing
• Exhalation / Expiration - giving out of air to the
surroundings
Breathing
Air that we breathe in
Air that we breathe out
Inhaled air
Exhaled air
Mechanism of breathing (Enrichment)
• Case 1:
When these rib muscles contract,
the rib cage expands. The
contraction of ribs and diaphragm
increases the volume of the chest
cavity. The space surrounding the
lungs increases so the lungs
expand. The pressure of the air of
the lungs falls and the air is drawn
into the lungs.
Mechanism of breathing (Enrichment)
• Case 2:
When the diaphragm muscles
and the rib muscles relax, the
chest cavity becomes smaller
and the lungs compress. The
pressure of the air in the lungs
increases, hence forcing air out
again.
Inhaled Air & Exhaled Air
water vapour
(variable)
carbon
dioxide (app.
0.03%)
nitrogen
(78%)
noble gases
(app. 1%)
carbon
dioxide
(4%)
oxygen (21%)
Composition of
inhaled air
water vapour
(variable)
noble gases
(app. 1%)
oxygen (16%)
composition of
exhaled air
nitrogen
(78%)
Inhaled Air & Exhaled Air
Inhaled air
Exhaled air
Oxygen
Contains 21% oxygen
Contain 16% oxygen
Carbon Dioxide
Contain 0.03% carbon
dioxide
Contains about 4% carbon
dioxide
Water vapour
Contain less water vapour
than exhaled air
Contain more water vapour
than inhaled air.
Question
• Is there more oxygen in inhaled air or exhaled air? Why?
• Is there more carbon dioxide in inhaled air or exhaled
air? Why?
• Is there more water vapour in inhaled air or exhaled air?
Why?
Video: Composition of air
Respiration & Photosynthesis
Both photosynthesis and aerobic
respiration are complex processes that are
alike in several ways.
But in many ways,
they are also different.
Respiration & Photosynthesis
Respiration
Photosynthesis
Uses oxygen
Produces oxygen
Does not need chlorophyll
Needs chlorophyll
Uses food
Produces food
Produce carbon dioxide
Uses carbon dioxide
Takes place all the time
Requires sunlight
Takes place in all living thing
Takes place in green plants
Takes place in all living cells
Take place in cells containing chlorophyll
Video: respiration
Respiration & Photosynthesis
Respiration
Photosynthesis
Energy is liberated
Energy is stored in carbohydrate
molecules
Oxygen is used and carbon dioxide and
water are given off
Carbon dioxide and water are used and
oxygen is given off
A destructive process, resulting in the
breakdown of carbohydrate molecules.
A constructive process, resulting in the
building up of carbohydrate molecules.
Occurs at all times in all cells,
independent of chlorophyll and sunlight
Occurs only in cells containing
chlorophyll and in the presence of
sunlight
-Both involve energy.
-Both involve enzymes.
Anaerobic Respiration
• Anaerobic respiration is the breakdown of food
substances in the absence of oxygen. Anaerobic
respiration releases less energy than aerobic respiration.
• Word equation for anaerobic respiration in humans:
Glucose
Lactic Acid +
Energy
• Word equation for anaerobic respiration in yeast:
Carbon +
Glucose
Ethanol + Energy
dioxide
Anaerobic Respiration
• Some bacteria are anaerobic.
• Anaerobic respiration in yeast is known as alcoholic
fermentation
- yeast respires anaerobically to convert sugar to alcohol
in the fermentation process.