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TISSUE

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TISSUE
Epithetical Tissue
(i) On the basis of cell layers
(a) When an epithelium has a single layer of cells it is called a simple epithelium.
(b) Where as a multiple tier of cells are known as stratified epithelium.
(ii) On the basis of simple shape of cells:
Ø  Cuboidal : its occurrence is in kidney tubules, salivery glands, inner lining of the cheek. Its main function is to give mechanical strength.
Ø  Columnar : its occurrence is in sweat gland, tear gland, salivary gland its main function is to gives mechanical strength concerned with secretions.
Ø  Squamous : when it forms a living as that of blood vessels, it is called endothelium.
Its main function is to protect the underlying parts from injury, entry of germs, etc.
Ø  Connective tissue : Its main function is to bind and support other tissues.
There are a few types of connective tissue.

Connective Tissue
Arelor
(i) Tendon
(ii) Ligament

Adipose Skeletal
(i) Bone
(ii) Cartilage

Fluid
(i) Blood
(ii) Lymph

A. Areolar tissue : It fills spaces inside organs found around muscles, blood vessels and nerves. Its main function is to joins skin to muscles, support internal organs, help in the repair of tissues. Whereas tendon’s main function is to connect muscles to bones and ligament is connects bones to each other.

B. Adipose tissue : Its occurrence is below skin, between internal organs and in the yellow bone Marrow. Its main function is to storage of fat and to conserve heat.

C. Skeletal tissue : Bone & cartilage occurrences is in nose, epigotis and in intervertebral disc of mammals. Its main function is to provide support and flexibility to body part. Whereas bone protects internal delicate organs provides attachments for muscles, bone marrow makes blood cells.

D. Fluid tissue : Blood & Lymph blood transport O2 nutrients, hormones to tissues and organs. Whereas leucocytes fight diseases and platelets help in cloting of blood. Lymph transport nutrients into the heart and it also forms the defense system of the body.

Muscular Tissue
It is specialized for ability to contract muscle cells.
Types of Muscular tissue:
A. Skeletal muscle: It attached primarily to bones. Its main function is to provide the force for locomotion and all other voluntary movements of the body.
B. Cardiac muscle: It occurs only in the heart. The contraction and relaxation of the heart muscles help to pump the blood and distribute it to the various parts of the body.
C. Smooth muscle: It can be found in stomach, intestines, and blood vessels these muscles cause slow and prolonged contractions which are involuntary.
D. Nervous tissue: This tissue is specialized with a capability to conduct electrical impulses and convey
information from one area of the body to another. Most of the nervous tissue (98%) is located in the central nervous system. The brain and spinal cord.
Types of Nervous Tissue
Ø  neurons
Ø  neuroglia

Important facts regarding animal tissue:-
Ø  Muscles contain special protein called contractile protein. Which contract and relax to cause
Ø  Fat storing adipose tissue is found below the skin and between internal organs.
Ø  Two bones are connected to each other by a tissue called ligament. This tissue is very elastic.
Ø  The skin, the living of the mouth, the living blood vessels, kidney tubules are all made up of epithelial tissue.
Ø  Voluntary muscles and cardiac muscles are richly supplied with blood whereas involuntary muscles are poorly supplied with blood.

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CELL

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CELL

Cell: It is the basic structural unit of life.
Cells were first discovered by Robert Hooke.
Note: The smallest cell is 0.1 to 0.5 micrometre in bacteria. The largest cell measuring 170 mm ×130 mm, is the egg of an ostrich.
Amoeba acquires its food through endocytosis.
1.       Prokaryotes cells - cells that have no defined nucleus
Eg: Bacteria & Blue-green Algae
2.       Eukaryote - cells which have definite nucleus
Eg: Other than Bacteria & Blue-green Algae
Compounds called proteins and phospholipids make up most of the cell membrane.

Diffusion-It is a process of movements of substance from a region of high concentration to a region where its concentration is low. Water also obeys the law of diffusion.
Eg: Substances like Co2 and O2 can move across the cell membranes by a process called diffusion.

Osmosis: The movement of water molecules is called osmosis. Osmosis is a special case of diffusion through a selectively permeable membrane.

Types of Osmosis:
1.       Hypotonic: more water will come into the cell than will leave. The cell is likely to swell up.
2.       Isotonic: the amount going in is the same as the amount going out of the cell.The cell will stay the same size.
3.       Hypertonic: more water leaves the cell than enters it. Therefore the cell will shrink.
When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.

Cytoplasm: It is the fluid that fills a cell. Scientists used to call the fluid protoplasm.

Ribosomes: It synthesis protein, and Endoplasmic reticulum sent these protein in various part of the cell. Whereas Smooth Endoplasmic reticulum helps in the manufacture of fats. It a made up of ribonucleic acid.

Functions of these proteins and fats:
·         Protein and fat (lipid) help in building the cell membranes. This process is known as membranes biogenesis.
·         Smooth Endoplasmic reticulum plays a crucial role in detoxifying many poisons and drugs.

Golgi apparatus :  It is another packaging organelle like the endoplasmic reticulum functions:
·         It is the organelle that builds lysosomes  (cells digestion machines).

Lysosomes(suicidal bag): It is a kind of waste disposal system of the cell.

Mitochondria(power house):  The energy required for various chemical activities headed for life is released by mitochondria in the form of ATP (adenosine-tri-phosphate) molecules.
Ø  ATP is known as the energy currency of the cell.
Ø  Mitochondria are strange organelles in the sense that they have their own DNA and ribosomes, therefore mitochondria are able to make their own protein.
Ø  Mitochondria is absent in bacteria and the red blood cells of mammals and higher animals.

Centrioles:  centrioles are concerned with cell division. It initiates cell division.

Plastids: These are present only in plant cells.
Types of plastids:-
Ø  Chromoplast(colour plastides)  impart colour to flowers and fruits.
Ø  Leucoplasts(white or colourless plastids) present  in which starch, oils and protein are stored.
Ø  Plastids are self-replicating. i.e. they have the power to divide, as they contain DNA, RNA and ribosomes.
Ø  Plastides contains the pigment chlorophyll that is known as chloroplast. It is the site for photo synthesis.
non –living parts with in the cell :-

Vacuoles: it is a fluid filled spaces enclosed by membranes. Its size in animal is small and in plant it is big.
Amino acids and sugars are stored in vacuoles.

Granules: It is not bounded by any membranes. It store fats, proteins and carbohydrates.

Cell nucleus: The cell nucleus acts like the brain of the cell. It helps control eating, movement
and reproduction. Not all cells have a nucleus.
The nucleus contain, the following components :
(a) Nuclear envelope (nuclear membrane)
(b) Chromatin : When the cell is in resting state there is something called chromatin in the nucleus. Chromatin is made up of DNA, RNA and nucleus protein. DNA and RNA are the nucleus acids inside the cell. When the cell is going to divide, the chromatin become very compact. It condenses when the chromatin comes together we can see the chromosomes.
(c) Chromosomes: Chromosomes make organisms what they are. They carry all the information used to help a cell grow, thrive and reproduce.
Ø  Chromosomes are made up of DNA.
Ø  Segments of DNA in specific patterns are called genes.
Ø  In prokaryotes, DNA floats in the cytoplasm in an area called the nucleoid.
Ø  Chromosomes are not always visible. They usually sit around uncoiled and as loose shards called chromation.
Ø  Chromosomes are usually found in pairs.
Ø  Human Beings probably have 46 chromosomes (23 pairs).
Ø  Peas only have 12, a dog has 78 chromosomes.
Ø  The number of chromosomes is not related to the intelligence or complexity of the creature.
(d) Nucleolus: It is a dense spherical granule contained within the nucleus.It stores proteins.

Cell Division
Organisms grow and reduce through cell  division.
There are two methods of replication mitosis and meiosis.
(a) Mitosis: It duplicates its DNA and the two new cells (daughter cells) have the same pieces and generic code. There are five steps in this process. You should remember the term PMATI. It breaks down to :
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
5. Interphase.
The main theme of meiosis is that there are two cell division. Mitosis has one division

Some important facts regarding cells :
Ø  Nerve cells in animals are the longest cells.
Ø  Smallest human cell is red blood cell.
Ø  Largest human cell is female ovum.
Ø  The single largest cell in the world is of an ostrich.
Ø  The smallest cells are those of the mycoplasma.
Ø  Every minute about 3 million cells in our body die.
Ø  Sieve tube in plants and the mature mammalian red blood cells do not have a nucleus.
Ø  The red blood cell carries respiratory gases.
Ø  Sieve cells in plants transport nutrients in plants.
Ø  The lysosomal enzymes of the sperm cells digest the limiting membranes of the ovum (egg). Thus the sperm is able to enter the ovum.
Ø  During the transformation of tadpole into frog. The embryonic tissues like gills and tail are digested by the lysosome.
Ø  Mitochondria contain DNA, hence capable of replication.
Ø  Matrix is a transparent, homogenous semi-fluid substance. In its active state. It remains saturated with water.

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Simple Harmonic Motion - Detailed Notes with Important Features & Related Terms!

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What is Simple Harmonic Motion?


A particle is said to execute simple harmonic motion if it moves to and fro about a mean position under the action of a restoring force which is directly proportional to its displacement from the mean position.

If the displacement of the oscillating body from the mean position is small, then
Restoring force ∝ Displacement
F  ∝  x     or     F = -kx
The above equation defines SHM. Where k is a positive constant called force constant or spring factor and is defined as the restoring force produced per unit displacement. The SI unit of k is Nm-1. the negative force represents that restoring force F always acts in the opposite direction of the displacement x.
According to Newton’s second law of motion,
simple harmonic motion - Testbook
So, Simple Harmonic Motion can also be defined as,
A particle is said to possess S.H.M if it moves to and fro about a mean position under an acceleration which is directly proportional to its displacement from the mean position. 
Some examples of Simple Harmonic Motion are:
  1. Oscillation of a loaded spring
  2. Vibrations of a tuning fork
  3. Vibrations of the balance wheel of a watch
  4. A freely suspended magnet in a uniform magnetic field oscillates in a simple harmonic motion.

Important Features of Simple Harmonic Motion

  1. The motion of the particle is periodic
  2. It is the oscillatory motion of the simplest kind in which the particle oscillates back and forth above its mean position with constant amplitude and fixed frequency.
  3. Restoring force acting on the particle is proportional to its displacement from the mean position.
  4. The force acting on the particle always opposes the increase in its displacement
  5. A simple harmonic motion can always be expressed in terms of a single harmonic function of sine or cosine.
Simple Harmonic Motion - Testbook

Important Terms Related to Simple Harmonic Motion

  1. Harmonic Oscillator: a particle executing simple harmonic motion is called a harmonic oscillator.
  2. Displacement: the distance of the oscillating particle from its mean position at any instant is called its displacement. It is denoted by x.
  3. Amplitude: the maximum displacement of the oscillating particle on either side of its mean is called its amplitude.
  4. Oscillation: one complete back and forth motion of a particle starting and ending at the same point is called a cycle or oscillation
  5. Time period: the time taken by a particle to complete one oscillation is called a time period.
  6. Frequency: it is defined as the number of oscillations completed per unit time by a particle.
  7. Angular Frequency: it is the quantity obtained by multiplying frequency by a factor of 2ℼ
  8. Phase: the phase of a vibrating particle at any instant gives the state of the particle as regards its position and the direction of motion at that instant. Suppose a simple harmonic equation is represented by:
x = Acos(ɷt + 𝚹)
Then phase of the particle 𝚹0 = ɷt + 𝚹

Summarized Notes On Simple Harmonic Motion

  1. A particle is said to execute simple harmonic motion if it moves to and fro about a mean position under the action of a restoring force which is directly proportional to its displacement from the mean position.
  2. For a simple harmonic motion, acceleration is directly proportional to the displacement
  3. The equation of SHM can be given by: x = Acos(ɷt + 𝚹)

Hope you understood the concept covered in this article Simple Harmonic Motion. 

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Rutherford Model of Atom - Learn Postulates & Drawbacks

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Rutherford Model of Atom
The idea of atom originated in ancient Greek and Indian cultures. The term atom was first coined by Democritus around 370 BC and defined it as the entity which is eternal, uncreated, and infinite in number. He stated that all objects in this universe is made of atoms, and their characteristics determine the qualities of the object itself.

After the genesis of this idea, many philosophers and scientists gave their own version of Atomic theory. The idea was even lost for a few centuries and was rediscovered by John Dalton at the end of the 18th century. Dalton even postulated some laws so as to justify the reasons behind chemical reactions.
With time rolling, new discoveries were made in this field. J.J Thomson was one such pioneer who not only discovered electron but also gave the first model of the atom which came to be known as the Plum Pudding Model. This model was based on then considered hypothesis that atoms are neutral in charge. So, when Thomson discovered electrons, he proposed that electrons are like plums that are embedded in a pudding of positive charge.
Later in the early 20th century (1908-1913), Hans Geiger and Ernest Marsden conducted the famous Gold Foil Experiment under the guidance of Ernest Rutherford. Rutherford was the student of J.J Thomson, and through his gold foil experiment proved that the plum pudding model is incorrect.

Gold Foil Experiment

When Rutherford discovered Protons, there was a need to update the existing model of atom as well. He conducted an experiment to determine the positions of subatomic particles in the atom. He along with Hans Geiger and Ernest Marsden conducted the Gold foil experiment.
In this experiment, rutherford bombarded high energy alpha particles on a very gold foil. He surrounded the gold foil with zinc sulfide screens to observe the deflections produced.
Rutherford Model of Atom - Testbook
The observations made from this experiment are described below:
  1. A large portion of the alpha beam passed through gold foil without getting deflected. This suggests that a major portion of the atom is empty.
  2. Just a fraction of alpha particles were deflected during this experiment suggesting that positive charge is not evenly distributed in the atom as assumed in the Plum Pudding model. But rather, it is concentrated over a very small area.
  3. The third observation made was that only very few alpha particle rays were deflected back at 180°. That means the volume of positive charge occupied in the atom is very small in comparison to the total volume of the atom itself.
Rutherford Model of Atom - Testbook

Postulates of Rutherford Model of Atom

  1. Atom is composed of negatively and positively charged particles called electrons and protons. The majority of the mass is concentrated at the center of the atom known as the nucleus.
  2. Electrons revolve around the nucleus at a very high speed in a fixed path known as orbits.
  3. Atoms are electrically neutral and the electrostatic attraction holds the electrons and protons together
  4. The volume occupied by the nucleus is very small in comparison to the volume occupied by atom.

Drawbacks of Rutherford Model of the Atom

The atomic model proposed by Rutherford is analogous to the solar system where the nucleus is like Sun and electrons are like planets revolving around it. But, this model failed to align with Clark Maxwell’s electromagnetic principles. According to this principle, a charged body moving under the influence of attractive forces loses energy continuously in the form of electromagnetic radiation. So,  electrons are a charged body and it should emit radiations while revolving around the nucleus. As a result of this, the electrons should lose energy at every turn, moving closer and closer to the nucleus and ultimately collapse. According to Maxwell’s calculations, it should take 10-8 seconds for an electron to collapse in the nucleus.
  1. However, this never happens. Thus, the Rutherford model of atom failed to explain the Stability of atom. 
  2. The Rutherford model of the atom also failed to explain the structure of atoms.
  3. Furthermore, the model also failed to explain the existence of certain definite lines in the hydrogen spectrum. If the electrons were to lose energy continuously, the atomic spectrum of hydrogen should have been continuous. However, the spectrum of hydrogen is found to be discontinuous in the form of characteristics lines of definite wavelengths.

Summarized Notes On Rutherford Model Of Atom

  1. J.J Thomson discovered electrons. He also proposed the plum pudding model.
  2. Ernest Rutherford discovered protons and through his Gold foil experiment proposed a new model of the atom.
  3. The new model of the atom that Ruderford proposed resembles the solar system.
  4. Most of the volume in an atom is empty.
We hope the above furnished article on Rutherford Model of Atom has helped you understand this important concept. 

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Vitamins and Their Sources

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We usually talk about vitamins but do we know what are vitamins? The vitamins are important as they perform various functions in the body. The deficiency of vitamins may take place as the food which you intake might not have enough of vitamin contents. This deficiency of vitamins hampers proper body functioning. To have a balanced diet enriched with the vitamins we need to know about the vitamins, their importance and sources. Read this article to know about different Vitamins and their sources and their importance.

Vitamins and Their Sources

There are 13 essential vitamins that are important for a human body. These vitamins are divided into two categories, fat-soluble and water-soluble vitamins. Given below in the table are the Different vitamins and their sources.
Fat-Soluble VitaminsWater-Soluble Vitamins
It is stored in the body’s fatty tissue.It is not stored in the body.
Fat-soluble vitamins are – A,D,E, KWater-soluble vitamins are – B1, B2, B3, B5, B6, B7, B9, B12, Vitamin C

Vitamins and Their Sources: What are Fat-Soluble Vitamins

The fat-soluble vitamins are similar to oil and do not dissolve in water. Fat-soluble vitamins are most abundant in high-fat foods and are much better absorbed into your bloodstream when you eat them with fat. Given below is the table with the list of different vitamins and their sources from which you can get, their importance for the body.
VitaminsImportanceSources
Vitamin A
  • This vitamin is vital for vision.
  • This vitamin provides healthy skin and mucous membranes.
  • It also improves bone and tooth growth.
  • It is vital for improving immunity.
  • Fortified milk
  • Cheese
  • Cream
  • Butter
  • fortified margarine
  • Eggs
  •  Liver
  • Leafy vegetables
  • Apricots
  •  Carrots
  • Sweet potatoes
  • Pumpkin.
Vitamin D
  • It is essential in proper absorption of calcium stored in bones.
  • Egg yolks
  • Liver
  • Fatty fish
  • Fortified milk
  • Fortified margarine
  • Sunlight.
Vitamin E
  • It protects cell walls.
  • Soyabean, corn e.t.c.
  • Leafy green vegetables
  • Wheat germ
  • Whole-grain products
  • Liver
  • Egg yolks
  • Nuts and seeds.
Vitamin K
  • It essential for proper blood clotting.
  • Kale
  • Collard greens
  • Spinach
  • Broccoli
  • Brussels sprouts
  • Asparagus
  • Produced in the intestinal tract by bacterias.

Vitamins and Their Sources: What are Water-Soluble Vitamins

Water-Soluble Vitamins are vitamins that can dissolve in water. These vitamins are carried to the body’s tissues but are not stored in the body. They are found in animal foods and plants or dietary supplements and should be taken daily. Both Vitamin C and members of the vitamin B complex are water-soluble. To know more about Water-Soluble Vitamins and their Sources, refer to the table given below.
VitaminsImportanceSources
Thiamine (vitamin B1)
  • The part of an enzyme which is required for energy metabolism.
  • It is significant in nerve functioning.
  • Pork
  • Whole-grain
  • Enriched breads
  • Cereals
  • Legumes
  • Nuts and seeds.
  • It is found in all nutritious food in moderate amounts.
Riboflavin(vitamin B2)
  • The part of an enzyme is needed for energy metabolism.
  • It is important for normal vision & skin health.
  • Milk and milk products
  • Leafy green vegetables
  • Whole-grain
  • Enriched  breads
  • Cereals.
Niacin (vitamin B3)This vitamin helps in maintaining:
  • healthy skin
  • nerves
  • digestive system.
  • Meat
  • Fish
  • Whole-grain
  • Enriched breads
  • Cereals
  • Mushrooms
  • Leafy green vegetables
  • Peanut butter.
Pantothenic acid
  • This vitamin is essential for the metabolism of food.
  • It is widespread in almost all food.
Biotin
  • Important in metabolism of proteins and carbohydrates.
  • It also helps in the production of hormones and cholesterol.
  • It is widespread in food.
  • It is produced in the intestinal tract by bacteria.
Pyridoxine (vitamin B6)
  • The part of an enzyme needed for protein metabolism.
  • It helps in making red blood cells.
  • Meat
  • Fish
  • Poultry
  • Vegetables
  • Fruits.
Folic acid
  • The part of an enzyme is needed for making DNA.
  • This also required for new cells i.e. red blood cells.
  • Leafy green vegetables
  • Legumes
  • Orange juice
  • Liver
  • It is now added to most refined grains.
Cobalamin (vitamin B12)
  • The part of an enzyme needed for making new cells.
  • It is important for nerve functioning.
  • Meat
  • Poultry
  • Fish
  • Seafood
  • Eggs
  • Milk and milk products
  • It is not found in plant foods.
Ascorbic acid (vitamin C)
  • This promotes healthy teeth & gums.
  • It is needed for healthy immune system.
  • The part of an enzyme is needed for protein metabolism.
  • It helps in iron absorption.
  • Citrus fruits
  • Cabbage family
  • Cantaloupe
  • Strawberries
  • Peppers
  • Tomatoes
  • Potatoes
  • Lettuce
  • Papayas
  • Mangoes
  • Kiwifruit.
Hope this article on vitamins and their sources was informative and helpful in your exam preparation. If you have any queries related to the article, do mention in the comments section.

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