LECTURE 5: RESPIRATION-I

CLASS X | SCIENCE | CHAPTER 1

      notes prepared by subhankar Karmakar

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The assimilated food is used as a fuel to get energy for various life processes and as a material for the growth and repair of the body. 

BREATHING

The mechanism by which organisms obtain oxygen from the air and release carbon dioxide is called breathing.  

RESPIRATION

The process of releasing energy from food is called respiration. The process of respiration involves taking in oxygen into the cells, using it for releasing energy by burning food, and then eliminating the waste products (carbon dioxide and water) from the body. The process of respiration which releases energy takes place inside the cell of the body. Respiration is essential for life because it provides energy for carrying out all the life processes which are necessary to keep the organisms alive. Respiration is opposite process of photosynthesis. 

Difference between Breathing and Respiration

• Respiration includes breathing as well as the oxydation of the food in the cells of the organism to release energy. 

• Breathing is a physical process whereas respiration also includes biochemical process of oxidation of food.

• The process of breathing involves lungs of the organism whereas the process of respiration also involves the mitochondria in the cells where food is oxidized to release energy.

STORAGE OF ENERGY RELEASED DURING RESPIRATION

The energy produced during respiration is stored in the form of ATP molecules in the cells of the body. 

ADP is a substance called Adenosine Di-phosphate and ATP is a substance called Adenosine Tri-phosphate. Both the molecules are present inside a cell. ATP has a high energy content.

(i) the energy release during respiration is used to make ATP molecules from ADP and inorganic phosphate. 

ADP (low energy) + Phosphate + Energy (from respiration) → ATP (high energy content)

Thus, energy is stored in the cells in the form of ATP. 

(ii) When the cell needs energy then ATP can be broken down using water to release energy. 

ATP → ADP + Phosphate + Energy

The energy equivalent to 30.5 kJ/mole is released in this process. This released energy by ATP is used to carry out all the endothermic reactions taking place in the cells. 

The energy stored in ATP is used by the body cells for various purposes like contraction of muscles, conduction of nerve impulses, synthesis of proteins and other activities related to the functioning of cells. 

"ATP is known as the energy currency of cells."

TYPES OF RESPIRATION

The respiration which uses oxygen is known as aerobic respiration and the respiration which takes place with out using oxygen is known as anaerobic respiration.  

The key compounds that we takes part in respiration are:

1. Glucose C₆H₁₂O₆ 

2. Pyruvic Acid or Pyruvate CH₃(CO)COOH

3. Lactic Acid CH₃(CHOH)COOH

GLYCOLYSIS

The oxidation of glucose to pyruvic acid or pyruvate is called Glycolysis. It occurs in cytoplasm. It does not require oxygen to complete. One molecule of glucose produces two molecules of pyruvic acid. 

In presence of oxygen, pyruvate is completely oxidised and produces carbon dioxide, water and a lots of energy. But if oxygen is not present, Pyruvate is converted to either ethanol and carbon dioxide (in plant cell) or lactic acid (in animal cell). Energy release is less. 

LACTIC ACID 

Lactic acid is also called as Lactate. It is a hydroxy carboxylic acid. 

AEROBIC RESPIRATION

1. The respiration which uses oxygen is called aerobic respiration. 

2. Here, glucose is completely broken down into carbon dioxide and water by oxidation.

3. It produces lots of energy and stored it in the form of ATP molecules.

4. Glucose first undergoes glycolysis to produce pyruvate in cytoplasm then pyruvate is broken down into carbon dioxide and water in the presence of oxygen in mitochondria and produces lots of energy. 

5. Mitochondria are the sites for aerobic respiration. 

6. Most of the living organisms uses aerobic respiration and hence can not live without oxygen. 

ANAEROBIC RESPIRATION

Anaerobic Respiration in Plants:

1. The respiration which takes place without oxygen is known as anaerobic respiration. 

2. Yeast and some bacteria obtain energy through anaerobic respiration. 

3. Glucose is broken down to pyruvate by  glycolysis in cytoplasm. Then, Pyruvate produces ethanol (C₂H₅OH) , carbon dioxide by fermentation and energy is stored in ATP molecules. 

4. The whole process of anaerobic respiration takes place in cytoplasm. 

5. Although human beings obtain energy through aerobic respiration but in certain cases we use anaerobic respiration too. During vigorous physical exercise, oxygen is used up faster in  the muscle cell in that case when oxygen supply becomes less our cells use anaerobic respiration.

6. Glucose is first gets converted into pyruvate by glycolysis and next it is converted to lactic acid and small amount of energy. 

Anaerobic Respiration in Animals:

LACTIC ACID FORMATION AND MUSCLE CRAMPS

During heavy physical activities our body uses anaerobic respiration and glucose gets converted into lactic acid. The accumulation of lactic acid in our muscle cell causes muscle cramps. We can get relief from cramps in muscles caused by heavy exercises and production of lactic acid by taking a hot water bath or massage. 

DIFFERENCES BETWEEN AEROBIC AND ANAEROBIC RESPIRATION

AEROBIC RESPIRATION	ANAEROBIC RESPIRATION
1.       Aerobic respiration takes place in the presence of Oxygen.	Anaerobic respiration takes place In the absence of Oxygen.
2.       Complete breakdown of the food occurs in aerobic respiration.	Partial breakdown of foods occurs in anaerobic respiration
3.       The end products in aerobic respiration are carbon dioxide and water.	The end products in anaerobic respiration may be ethanol and carbon dioxide (in yeasts) or lactic acid (in animals).
4.       Aerobic respiration produces a considerable amount of energy.	Much less energy is produced in anaerobic respiration.

LECTURE 4: NUTRITION IN HUMAN BEINGS (CLASS X)

CLASS X   |    SCIENCE    |    LIFE PROCESSES

      Notes prepared by Subhankar Karmakar

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• HUMAN DIGESTIVE SYSTEM

The various organs of the human digestive system in sequence are:

Mouth, Oesophagus, Stomach, Small Intestine and Large Intestine. The glands which are associated with the human digestive system and form a part of the human digestive system are : Salivary glands, Liver and Pancreas. 

• Alimentary Canal:

Human alimentary canal which runs from mouth to anus is about 9 metres long tube. The ducts of various glands open into the alimentary canal. 

• 1. INGESTION

The organ for human ingestion is called mouth.

• 2. DIGESTION 

In human beings, digestion of food begins in the mouth itself. 

• A. Buccal Cavity:

The mouth cavity is also known as buccal cavity. It contains teeth, tongue and  salivary glands. The teeth cut the food, chew and grind it. Tongue mixed the small pieces of food mixed with saliva. Saliva contains an enzyme called Salivary Amylase, which converts Starch into sugar. Hence, Salivary glands helps chemical digestion by secreting enzymes. But due to short period of time the digestion remains incompleted. 

• B. Oesophagus

The food pipe is known as oesophagus. It carries food to the stomach. 

• Peristaltic movement
• The walls of the food pipe/oesophagus have muscles which can contract and expand alternatively. When slightly digested food enters the food pipe, the walls of the food pipe start contraction and expansion movements. This contraction and expansion movements of the food pipe walls are known as  peristaltic movement. 
• Peristaltic movement moves the food in all digestive organs throughout the alimentary canal. 

• C. Stomach
• Stomach is a J shaped organ present in the left side of the abdomen. Here food is broken down into a semi-solid paste. 

• Gastric Juice

Stomach wall contains three tubular glands which secrete gastric juice. The gastric juice contains hydrochloric acid, the pepsin enzyme and mucus. The gastric juice is acidic in nature. 

• Function of Pepsin enzyme

In the acidic medium pepsin breaks down the proteins into smaller molecules, often into amino acids. Therefore, the digestion of proteins start at stomach. 

• Function of Hydrochloric acid

Pepsin is only activated in an acidic medium. The function of the Hydrochloric acid in stomach is to make the gastric juice acidic, so that pepsin can start digesting proteins molecules. Another function of the hydrochloric acid is to kill any bacteria that may enter into the stomach through the food. 

• Function of mucus

The mucus helps to protect the stomach walls from its own secretion of hydrochloric acids. If mucus is not secreted, hydrochloric acid will cause the erosion of the inner lining of stomach leading to the formation of ulcers in the stomach. 

• Sphincter Muscle

The partially digested food from stomach passes to the small intestine. The exit of food from stomach is regulated by a gate called sphincter muscle which releases it in small amounts into the small intestine. 

• D. Small Intestine

The small intestine is the largest part of the alimentary canal of about 6.5 m long in an adult man. It is very narrow hence, it is called small intestine. It is arranged in a coil form. The small intestine in human beings is the site of complete digestion of food like carbohydrates, proteins and fats. 

Difference in small intestine in Herbivores and Carnivores

Herbivores eat cellulose which is difficult to digest. Hence, herbivores have longer small intestine, whereas carnivores eat meat which is easier to digest so they have relatively shorter small intestine. 

Secretions from two glands in small intestine: Liver and Pancreas

• Liver : Liver is a gland that secretes bile. Bile is a greenish yellow liquid made in the liver and stored in the gall bladder. Bile is alkaline in nature and conatains salts which helps to break the fats/ lipids present in the food. 

Functions of Bile

Bile performs two functions. 

• (i) it makes the acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it.
• (ii) Bile salts break the fats present in the food into small globules so that enzymes can act and digest it. 

• Pancreas

Pancreas is a large gland which lies parallel to and beneath the stomach. Pancreas secretes pancreatic juice which contains digestive enzymes like pancreatic amylase, trypsin and lipase. 

Pancreatic amylase breaks down the starch.

Trypsin digests the proteins and lipase breaks down the emulsified fats. 

Functions of intestinal juice

• The intestinal juice contains many enzymes which converts complex carbohydrates into glucose, proteins into simple amino acids and fats into fatty acids and glycerol all of which are water soluble small molecules. 
• The chemical digestion of food is brought about by biological catalysts called enzymes. 

• 3. ABSORPTION

• The small intestine is the main region for the absorption of digested food. After digestion, the molecules become so small that they can pass through the walls of the small intestine which contain blood capillaries and go to our blood. 
• The inner surface of small intestine has millions of tiny finger like projections called villi.  The presence of villi gives the inner walls of small intestine a very large surface area which helps in the rapid absorption of digested food. 

• 4. ASSIMILATION

• The blood carries the digested food to all the parts of the body where it becomes assimilated as part of the cells and it is used by the body cells for obtaining energy as well as for growth and repair of the body. 
• The unused part of the food is stored in the liver in the form of a carbohydrate known as glycogen. The stored glycogen can be used when it is needed. 

• 5. EGESTION

• A part our food which can not be digested passes from small intestine to a wider tube which is called large intestine. It is called large as it is wider. 
• The walls of the large intestine also have villi which absorb most of the water from the undigested part of the food and hence, it becomes solid. 
• The last part of the large intestine is called rectum which stores the undigested food for some time and then be expelled from our body as stool. This process is known as Egestion or defecation and it is controlled by anal sphincter. 

Dental Caries

1. The hard, outer covering of a tooth is called Enamel. It is harder than bones. 

2. The part of tooth below enamel is called Dentine. Dentine is similar to bone. 

3. Inside the dentine, there is pulp cavity, which contains nerves and blood vessels. 

4. Formation of small cavities in the teeth due to the action of acid forming bacteria and improper dental care is called dental caries. 

5. If the teeth are not cleaned regularly, they become covered with a sticky, yellowish layer of foid particles and bacteria cells called dental plaque. 

Extra Notes:

The long, tube-like organ that is connected to the small intestine at one end and the anus at the other is called large intestine. The large intestine has four parts: cecum, colon, rectum, and anal canal. Partly digested food moves through the cecum into the colon, where water and some nutrients and electrolytes are removed. The remaining material, solid waste called stool, moves through the colon, is stored in the rectum, and leaves the body through the anal canal and anus. 

POLYATOMIC IONS

POLY-ATOMIC IONS

Ions that contained atoms of more than one element is known as poly-atomic ions.

Polyatomic ions are ions that are composed of two or more atoms that are covalently bonded together, and they carry an overall electric charge. These ions can be either positively or negatively charged, and they play an important role in chemistry and biochemistry.

Some examples of commonly encountered polyatomic ions include sulfate (SO₄^-2), nitrate (NO₃^-), carbonate (CO₃^-2), ammonium (NH₄⁺), and phosphate (PO₄^-3).

Polyatomic ions are often involved in chemical reactions, where they act as reactants, products, or catalysts. For example, sulfate is often used as a reactant in the production of fertilizers, while phosphate is a key component of DNA and ATP (adenosine triphosphate), which is the primary energy source for most biological processes.

Polyatomic ions are also important in the context of acid-base chemistry, as they can act as either acids or bases depending on the situation. For example, nitrate can act as a base in the presence of a strong acid, while ammonium can act as an acid in the presence of a strong base.

Overall, polyatomic ions play an important role in many areas of chemistry and biology, and a good understanding of their properties and behaviors is essential for anyone studying these subjects.

NAME	SYMBOLS	VALENCY
HYDROXIDE	OH	-1
ACETATE	CH₃COO	-1
CYANIDE	CN	-1
CHLORATE	ClO3	-1
CHLORITE	ClO2	-1
NITRATE	NO3	-1
NITRITE	NO2	-1
SULPHATE	SO4	-2
SULPHITE	SO3	-2
PHOSPHATE	PO4	-3
PHOSPHITE	PO3	-3
PERMANGANATE	MnO4	-1
HYDROGEN CARBONATE	HCO3	-1
CARBONATE	CO3	-2
SILICATE	SiO3	-2
CHROMATE	CrO4	-2
DICHROMATE	Cr2O7	-2
AMMONIUM	NH4	+1

Examples of Compounds having hydroxide (OH) ions

 

Compound Name	Formula	Uses
Sodium Hydroxide	NaOH	It is also called Caustic Soda. Used in manufacturing of paper, textiles, soaps etc.
Potassium Hydroxide	KOH	Used in the manufacturing of soaps and detergents.
Calcium Hydroxide	Ca(OH)2	It is also called Slaked Lime. Used as a construction materials.
Aluminium Hydroxide	Al(OH)3	Used in Antacid to neutralize acidity in stomach and treat ulcers.
Magnesium Hydroxide	Mg(OH)2	Used in Antacid to neutralize acidity and indigestion, heartburn.
Ammonium Hydroxide	NH4OH	Used in as Cleaning agent.
Barium Hydroxide	Ba(OH)2	Used in the production of Lubricants.

 

Examples of Compounds having Acetate (CH₃COO) ions

 

Compound Name	Formula	Uses
Sodium Acetate	CH3COONa
Acetic Acid	CH3COOH

 

Examples of Compounds having Cyanide (CN) ions

 

Compound Name	Formula	Uses
Potassium Cyanide	KCN
Hydrogen Cyanide	HCN

 

Examples of Compounds having Chlorate (ClO₃) ions

 

Compound Name	Formula	Uses
Potassium Chlorate	KClO3
Barium  Chlorate	Ba(ClO3)2
Calcium Chlorate	Ca(ClO3)2
Iron(III) Chlorate	Fe(ClO3)3
Zinc Chlorate	Zn(ClO3)

EXAMPLE: SOME COMMON COMPOUNDS CONTAINING HYDROXIDE IONS

Sodium Hydroxide NaOH

Potassium Hydroxide KOH

Calcium Hydroxide Ca(OH)₂

Aluminium Hydroxide Al(OH)₃

Acetate      (CH₃COO) (-1)

Sodium Acetate CH₃COONa

Cyanide.  (CN) (-1)

Potassium Cyanide KCN

Hydrogen Cyanide HCN

Chlorate (ClO₃) (-1)

Potassium Chlorate KClO₃

Chlorite (ClO₂) (-1)

Nitrate.    (NO₃) (-1)

Nitric Acid HNO₃

Potassium Nitrate KNO₃

Sodium Nitrate NaNO₃

Nitrite.     (NO₂) (-1)

Nitrous Acid HNO₂

Sulphate (SO₄) (-2)

Sodium Sulphate Na₂SO₄

Barium Sulphate BaSO₄

Zinc Sulphate ZnSO₄

Copper Sulphate CuSO₄

Sulphite.  (SO₃) (-2)

Phosphate (PO₄) (-3)

Phosphite. (PO₃) (-3)

Permanganate (MnO₄) (-1)

Hydrogen Carbonate (HCO₃) (-1)

Carbonate (CO₃) (-2)

Silicate (SiO₃) (-2)

Chromate (CrO₄) (-2)

Dichromate (Cr₂O₇) (-2)

Aluminate (AlO₃) (-3)

Ammonium (NH₄) (+1)