Osmoregulation and Homeostasis | HSEB Notes of Zoology Class 12

Zoology | Biology
HSEB Notes on Osmoregulation and Homeostasis
Unit : Excretion and Osmoregulation
Class : 12

In case of human hypertonic urine is excreted. This minimizes the water loss from their body. The filtrate fluid in Bowman's capsule (isotonic) passes through the tubules of nephrones. Then a large amount of water and solutes are reabsorbed during this course. During cold month, hypotonic urine is excreted but in warmer month hypertonic urine is excreted due to sweating.

Internal Structure of Monocot Root | Class 12 Botany Notes

Botany | Biology
HSEB Notes on Internal Structure of Monocot Root
Class : 12

Monocot root lacks of secondary growth and shows following internal structures:

 

EPIDERMIS 

It is composed of a thin walled,compactly arranged single layer of parenchymatous cells without intercellular space.it also gives rise to unicellular root hair.cuticle and stomata are absent in monocot root. epidermal cells and root hair take part in absorption of water and minerals from soil. multilayer epidermis is found in epiphytic plants like orchid and is called as velamen.pnematodes of velamen help in gaseous exchange. 

DNA Replication Process | HSEB Notes of Botany Class 12 Biology

Botany | Biology
HSEB Notes on Process of DNA Replication
Class : 12

The process of synthesis of DNA molecule from preexisting dna is called dna replication.  NA replication may occur by following process: 

1.semi-conservative replication 

2.conservative replication 

3.dispersive replication 

Semi-conservative mode of DNA replication

Enzymes involved in semi conservative DNA replication: 

Helicase- helicase enzyme breaks the hydrogen bonds formed between bases of nucleotides

Physiology of Digestion | Class 12 Zoology Notes

Biology | Zoology
HSEB Notes on Physiology of digestion
Lesson :  Digestion
Class : 12

Man is omnivorous. It means man depends on plant materials and animal products. The food contains carbohydrate, protein and fats. The food is digested at different parts of alimentary canal.

Digestion in mouth

In mouth, the food is mixed with the saliva from salivary gland. Saliva contains the enzyme called salivary amylase. Salivary amylase acts on carbohydrate and changes some of carbohydrate into maltose, isomaltose and limit dextrine. Food remains in mouth for a short time so digestion is not complete. 

Digestive Glands Associated with Alimentary Canal of Human | Class 12 Biology Notes

Biology | Zoology
HSEB Notes on Digestive glands
Lesson :  Digestion
Class : 12

Glands associated with alimentary canal.

Salivary glands

There are three pairs of salivary glands. There is one pair of Parotid gland. It is the largest of the salivary glands. It is situated near the ears. Stenson’s duct of Parotid gland open near the upper 2nd molar. One pair of sublingual glands are small and situated beneath tongue. Ducts of Rivinus open into floor of oral cavity. One pair of submandibular(also submaxillary) glands are medium sized and situated at angle of lower jaw. Warton’s duct open near the lower central incisors.

Alimentary Canal in Digestive System of Human Beings | HSEB Notes Class 12 Zoology

Biology | Zoology
HSEB Notes on Digestive System of Human Beings
Lesson :  Digestion
Class : 12

Human beings are heterotrophic. It means they can not manufacture their food and depend upon plants or other animals. They have holozoic type of nutrition. The nutrition is animal like. Human beings are omnivorous in nature. The digestive system consists of alimentary canal and digestive glands. Alimentary canal is complete and has well defined regions. It is concerned with ingestion, digestion, absorption and egestion of waste material.

Physiology of Respiration | HSEB Notes of Biology Class 12

Biology | Zoology
HSEB Notes on Physiology of respiration
Lesson :  Respiration
Class : 12

Physiology of respiration can be studied under following headings.

1. external respiration

2. transportation of O2 by blood

3. internal respiration

4. transportation of CO2 by blood.

External respiration - it is uptake of O2 and release of CO2. It takes place in the lungs called breathing. 

Transport of O2 by blood - RBC of blood contain haemoglobin as respiratory pigment. Human blood contains nearly 150 gram of Hb per 100 ml. haemoglobin readily combines with and dissociates to form free Oxygen. => Hb + O2 == HbO2

Difference between Inhalation and Exhalation | Class 12 Biology Notes

Biology | Zoology
HSEB Notes on Respiratory Organs and Mechanisms of Breathing
Lesson :  Respiration
Class : 12

Difference between inhalation and exhalation

Please compare the point of Inhalation with the point of Exhalation 

Inhalation 

1. Taking in of atmospheric air 

2. contraction of external intercostal muscle or inspiratory muscle and relaxation of internal intercostals muscle.

Respiratory Organs and Mechanisms of Breathing | HSEB Notes of Biology Class 12

Biology | Zoology
HSEB Notes on Respiratory Organs and Mechanisms of Breathing
Lesson :  Respiration
Class : 12

Respiratory organs 

There is a pair of spongy conical hollow bags enclosed in pleural cavities called lungs. The plural cavities are lined by tough, flexible and transparent membranes called pleura. The plura is double walled. The outer membrane is parietal and inner membrane is visceral membrane. These membranes protect lungs and stop leaking of air into thoracic cavity. The fluid secreted by pleura reduces the friction during breathing movement. The lungs are capable of great

Respiration and Its Types | HSEB Notes of Biology Class 12

Biology | Zoology
HSEB Notes on Respiration and Its Types
Lesson :  Respiration
Class : 12

Respiration can be defined as a biochemical process in which organic compounds are oxidized to liberate energy. Energy is released in a step wise process. The energy is trapped in a chemical bonds of adenosine triphosphate ATP molecules. ATP is instant sources as universal energy carriers. It is a catabolic process.

Urine Formation | HSEB Notes of Biology, Zoology Class 12

Biology | Zoology
HSEB Notes on Urine Formation
Lesson :  Excretion and Osmoregulation
Class : 12

Three basic steps 1.Glomerular filtration or ultra filtration  2. Selective reabsorption  3. Tubular secretion

Glomerular filtration smaller diameter of efferent arteriole than that of afferent arteriole increases the blood pressure in Glomerulus. Hydrostatic pressure of about 55 mm of Hg is developed which can force out the different substances of blood into the lumen of Bowman’s capsule. This is assisted by the thin and closely applied walls of Bowman’s capsule and walls of capillaries. The hydrostatic pressure is opposed by osmotic pressure of about 30 mm of Hg and filtrate pressure of about 15 mm of Hg. The net filtration pressure is of about 10 mm of Hg. 

Structure of Kidney and Nephron | HSEB Notes of Biology Class 11 Zoology

Biology | Zoology
HSEB Notes on Structure of Kidney and Nephron
Lesson :  Excretion and Osmoregulation
Class : 12

A pair of kidneys located on either side of back bone in the abdominal cavity. The left kidney is positioned higher than the right one. At anterior end of kidney adrenal gland is present. Each kidney is bean shaped, about 10 cm long and 6 cm wide and weighs about 150 gm. At the concave side, there is a depression called hilum from where renal artery enters and renal vein and ureters pass out.

Physiology of Excretion | HSEB Notes of Biology Class 12 | Zoology

Biology | Zoology
HSEB Notes Physiology of Excretion
Lesson :  Excretion and osmoregulation
Class : 12

Excretion is the removal of metabolic waste from body particularly nitrogenous waste. Skin, lungs, liver are considered as accessory excretory organs while kidney is the most important one which forms as important part of the4 urinary system also. Urinary system of man consists of  1. Kidneys   2. Ureters   3. Urinary bladder    4. Urethra 

HSEB Notes on Venous System of Circulatory System of Human Beings Class 12

Biology | Zoology
HSEB Notes on Venous system | Circulation
Class : 12

All veins in the body together make venous system. This system is for collection of pure blood from lungs and impure blood from rest of the parts of body. Four pulmonary veins collect pure blood form lungs and open into left atrium. Superior venacava collect blood from anterior part of body. It is made by different veins. Right and left innominate veins join to form superior venacava. Each innominate is made by right and left external and internal jugular veins collecting blood from head and brain. The right and left subclavians collect from hand. The subclavian is again made by axillary and cephalic veings. Azygous vein collects from chest region in the right side. Hemiazygous collect from left side . both open into superior venacava. Inferior venacava is made by different veins. Two short and thick hepatic veins collect blood from liver. 

HSEb Notes on Arterial System | Circulation Class 12 Zoology

Biology | Zoology
HSEB Notes on Arterial system | Circulation
Class : 12

There are many arteries in the body. They distribute blood to different parts of body. All these arteries together make arterial system. This system supply pure blood to body organs and impure blood to lungs.  Pulmonary aorta arises from right ventricle. It divides to two branches. They are pulmonary arteries. These arteries supply impure blood to two lungs. 

HSEB Notes on Origin and Conduction of Heart Beat | Class 12 Zoology

Biology | Zoology
HSEB Notes on Origin and conduction of Heart Beat
Class : 12

In the wall of right atrium, there is a special node called Sino Atrial node(SA node). It is self excitatory. It is the point of origin of heart beat. It is also called Pace maker. It is natural Pace maker. The heart cant work without it. If it is injured or damaged artificial pace maker is implanted. 

Near inter atrial septum, there is Atrioventricular node (AV node). It receives the impulses in the form of wave and passes it to Purkinje’s system. This system consists of Bundle of His, purkinje fibres. With the help of this system impulses are carried to the wall of ventricle. Then both ventricles contract pumping out blood. 

Some terms Related to Circulatory System | Zoology Class 12

Biology | Zoology
HSEB Notes on Circulation
Class : 12

Some terms related to Circulation system of Heart

Heart beat

Heart beat consists of one contraction phase and one relaxation phase. During the contraction phase, there is maximum point(peak period) which is known as systole. During the relaxation phase also, there is minimum point which is known as diastole. One heart beat is completed in about 0.8 second time. 

HSEB Notes on Course of Circulation | Zoology, Biology Class 12

Biology | Zoology
HSEB Notes on Course of circulation 

Class : 12

Course of circulation 

1. Pulmonary Circulation 

It is the circulation between the heart and lungs. The impure blood(deoxygenated blood) is pumped out from the right ventricle. The pulmonary trunk takes the impure blood. The pulmonary trunk divides into two pulmonary arteries. The pulmonary arteries supply impure blood to the two lungs. In side the lungs, the impure blood is purified. After the purification, the pure blood is returned to the heart through the pulmonary veins. The pulmonary veins open into the left atrium.

HSEB Notes on Physiology of Circulation Class 12

Biology | Zoogy
HSEB Notes on Circulation
Class : 12

Physiology of circulation

Human body is fairly complex and performs wide range of activities. Different organs of body are located far away and may have no connection at all. Our body needs a specialized system of circulation which can connect these organs supplying nutrients, gases, hormones and carrying wastes from these organs. This system of circulation also performs the functions like regulation of things and protection. The system of circulation of some extra cellular fluid is flowing in the body. The structures associated with circulation constitute circulatory system.