blog10d2: July 2013

bio respiration classwork for who don t have it

copy it in word and print then the pics will also come

_________________________________________________________________________________

CLASS-XD&H CLASS WORK-2

DATE 14-5-2013 RESPIRATION

Respiration is a catabolic process, during which glucose molecule is oxidized in the presence of specific enzymes to release energy for various metabolic processes – It is completed in broadly two steps external and internal respiration.

1) External respiration: It involves exchange of gases in the respiratory organ / surface. It takes place in different ways in different organisms

i) In plants: Exchange of gases takes place through stomata large inter cellular spaces ensure that all cells are in contact with air. Exchange of CO₂ and O₂ takes place by diffusion. They can go into cells or away from them and out into the air. The direction of diffusion depends upon the environmental conditions and the requirement of the plants. At night, when there is no photosynthesis occurring, CO₂ elimination is the major exchange. During the day, CO₂ generated during respiration is used for photosynthesis. Hence there is no CO₂ release. Instead O₂ is released

ii) In aquatic animals: These animals use oxygen dissolved in water. Amount of dissolved oxygen is fairly low in water as compared to the amount of O₂ in the air So, in order to take in maximum oxygen, the rate of breathing is very fast in aquatic animals as compared to the terrestrial organisms

iii) In terrestrial organisms:- These animals use the O2 present in the atmosphere. It is absorbed by different organs in different animals. Example- in earthworm, exchange of gases takes place through skin, in human beings, through lungs.

The characteristics of a good respiratory surface

· Respiratory surface should have a large surface area. The surface where ex- change of gases has to take place should be very thin and delicate

· Respiratory surface should be richly supplied with blood capillaries

· The surface is usually within the body, so there has to be a passage to take in the air to this area & there should be a mechanism for moving the air in and out of this area.

iv) In human beings: Human beings have a well-developed respiratory system to take in air rich in oxygen & give out air rich in CO₂. This system consists of a pair of nostrils, nasal cavities, pharynx, trachea, bronchi, bronchioles, leading to alveoli in the lungs. The air is taken into the body through the nostrils. The nasal cavity has fine hair (cilia) & mucus glands..Air is filtered by these hair to remove dust particles & other impurities as well as it is made warm. From the nasal cavities the air comes to pharynx which leads into larynx (larynx is the voice box- it has vocal cords) This further leads into trachea (trachea is lined with rings of cartilage to prevent the air passage from collapsing) Trachea divides into two branches called bronchi. Each bronchus enter the respective lung. Inside each lung the bronchus divides & redivides into bronchioles.. Each bronchiole ends into balloon like structures called alveoli. The alveoli are very thin they provide a large surface area for exchange of respiratory gases and are richly supplied with blood vessels. There is a pair of lungs situated in the thoracic cavity. Each lung is a bag like spongy structure which rests on a sheet of membrane called diaphragm. Lungs are covered and protected by pleural membrane. The gap between the two membranes is filled with pleural fluid.

http://www.gosh.nhs.uk/EasysiteWeb/getresource.axd?AssetID=101031&type=custom&servicetype=Inline&customSizeId=21

MECHANISM OF BREATHING AND

RESPIRATION IN HUMAN BEINGS

1) INHALATION: It is a process of taking in atmospheric air into the lungs. During this phase rib muscles contract so that the ribs move upward & outward. Diaphragm which is dome-shaped, contracts and becomes flat, the volume of the chest cavity increases while the pressure of the air in the thoracic cavity deceases. Air is sucked into the lungs which fills the spaces in the alveoli. Inhalation is a physical process.

2) EXHALATION: It is the process in which CO₂ is expelled from the lungs. The rib muscles relax & move inward & downward. The diaphragm becomes dome-shaped. Volume of chest cavity decreases. The pressure of air inside the chest cavity increases. Air rich in CO₂ rushes out of the chest cavity. Exhalation is a physical process which involutes giving out air rich in CO₂ from the body (expiration).

NOTE: During breathing cycle when air is taken and let out, the lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for carton -dioxide to be released from them.

EXCHANGE OF GASES IN ALVEOLI / TRANSPORTATION

Exchange of gases takes place in two levels: at the surface of the alveoli and at the cellular level

1) Oxygen rich air is inhaled into the body. It reaches the surface of the alveoli. The concentration of O₂ is more inside the alveoli than in the blood present in the capillaries on the alveolar surface. Therefore O₂ diffuses into the capillaries and combines with haemoglobin of the RBCs to from a compound. Oxyhaemoglobin.

2) It is carried in this form to the cells. The concentration of O₂ is more outside the cell than inside so O₂diffuses into the cell as oxyhaemoglobin. Inside the cell it breaks to form oxygen & hemoglobin separately. This O₂ is then used to break down food into energy and CO₂is produced inside the cell

3) Concentration of CO₂ increases inside the cell. It diffuses out into the blood where it is taken to the alveoli dissolved in the blood plasma because CO₂is more souble in water than O₂ So it is transported in the dissolved form by the plasma of the blood. From the alveoli, CO₂ is exhaled out.

CELLULAR RESPIRATION

It is the biochemical process during which glucose molecule is oxidized inside the cell in the presence of specific enzymes at optimum temperature to release energy in the form of ATP molecules. Cellular respiration may be divided into 2 categories depending upon the availability of (atmospheric) oxygen.

1) AEROBIC RESPIRATION: The oxidative breakdown of respiratory substrate (glucose) with the help of oxygen is known as aerobic respiration. In this process, C₆H₁₂O₆ is completely converted into CO₂ and H₂O, In most of the eukaryotic organisms some part of aerobic respiration (glycolysis) occurs in the cytoplasm (2ATP) and the major part (Krebs cycle) occurs inside the mitochondrion matrix. In the cytoplasm, glucose is broken down into pyruvic acid a 3-carbon compound by the process of glycolysis. In presence of O₂ this pyruvate enters into mitochondria where it is completely broken down. Energy of 36 ATP is released.

Glycoly sis Krebs cycle

________________ Pyruvic acid __________________ CO₂ + H₂O +energy

Glucose (in cytoplasm) (Mitochondria)

[In absence of O₂] [In presence Of O₂]

2) ANAEROBIC RESPIRATION: Oxidation of respiratory substrate in absence of O₂ is termed as anaerobic respiration. It involves incomplete breakdown of glucose in which the end products such as ethyl alcohol (ethanol) or lactic acid are formed & CO₂ is released. In this process the initial breakdown of glucose to pyruvic acid (glycolysis) inside the cytoplasm is the same, but further breakdown of pyruvic acid in absence of O₂results in production of ethyl alcohol and lactic acid.

Anaerobic respiration occurs in certain microorganism such as bacteria and yeast (In yeast it is called fermentation). They get energy in the absence of O₂

Glycolysis

Glucose _______________ Pyruvic acid ______ C₂H₅OH + CO₂+ energy

(in cytoplasm)

[In absence of O₂ ] [In absence of O₂)

Anaerobic respiration also occurs inside the muscles during vigorous muscular activities, this usually occurs during the phase when O₂ gets used up faster than it is available for breakdown of respiratory substrate. Glucose breaks down into lactic acid with release of energy.

Glycolysis

Glucose __________ Pyruvic acid _______ Lactic acid + Energy

(in cytoplasm) (In muscle cells)

[In absence of O₂)

Therefore the overall reactions are:

1) AEROBIC RESPIRATION: C₆ H₁₂ O₆ + 6O₂ → 6CO₂ + 12H₂O + 38 ATP energy

2) ANAEROBIC RESPIRATION / FERMENTATION:

C₆H₁₂O₆→ 2C₂H₅OH + 2CO₂ +2 ATP energy

During lack of O₂ in muscle cells, C₆ H₁₂ O₆ → C₃ H₆O₃ + 2 ATP energy

NOTE:- BREAKDOWN OF GLUCOSE BY VARIOUS PATHWAYS:

ACTIVITY 6.3

AIM:- To show that the air we breathe out is richer in CO₂ then the air around us.

MATERIALS REQUIRED:- Two test tubes, freshly prepared lime water, glass tube or rubber tube, syringe

METHOD:-

1) Take two test tubes and label them as A and B. Pour some freshly prepared lime water in each of the test tubes.

2) Now blow air into tube A through the mouth with the help of a glass tube & observe.

3) Pass air in tube B with a syringe & observe again.

OBSERVATION RESULT:-

1) Lime water in test tube A turns milky faster showing that we exhale more carbon dioxide as lime water in tube B takes a longer time to turn milky.

2) Carbon dioxide combines with calcium hydroxide to form a white precipitate of CaCO₃

ACTIVITY 6.4

AIM:- To show the process of fermentation (anaerobic respiration in yeast)

MATERIALS REQUIRED:- Fruit juice / sugar solution, yeast, bent glass tube, test tube one holed cork / rubber stopper and lime water

METHOD:-

1) Take some fruit juice or sugar solution in a test tube, & add some yeast into it close the opening of the test tube with a one holed cork.

2) Insert a bent glass tube in the cork & dip the other end of the tube into the test tube containing lime water. Observe after few hours.

OBSERVATION

Lime water turns milky. When we open the stopper, we get smell of alcohol

RESULT

1) This shows that CO₂ is liberated from the mixture of sugar / Fruit juice with yeast.

2) Fermentation of sugar results in production of ethyl alcohol & carbon-dioxide. This process occurred in the absence of O₂as the cork was tightly fitted.

AEROBIC RESPIRATION	ANAEROBIC RESPIRATION
Aerobic respiration occurs in presence of O₂, where oxygen is utilized.	1) Anaerobic respiration occurs mainly in the absence of oxygen
Complete breakdown of glucose takes place.	2) Incomplete breakdown of glucose occurs
End products are CO₂ water vapour & 38 molecules of ATP	3) End products are either ethyl alcohol, CO2 & 2ATP or lactic acid & 2ATP
Occurs both in cytoplasm and mitochondria	4) Occurs only in cytoplasm
5) It occurs in all higher plant & animals.	5) Occurs in organisms like bacteria yeast or in muscle cells during vigorous exercise
C₆H₁₂O₆+6O₂→ 6CO₂+12H₂O+38 ATP	C₆H₁₂O₆→ 2C₂H₅OH + 2CO₂ +2ATP (yeast) C₆H₁₂O₆→ C₃H₆O₃ + 2ATP (muscles)