CONCEPT: Cell
Cell is the basic building block of an organism. It was discovered by Robert Hooke in 1665. Cell can be as small as 0.1 Micrometer to several millimeters. It might be circular, irregular or even extended like that of Nerve cell. When a group of cell perform a particular function it is called Tissue. When a group of tissue performs a particular function it is called Organ. And when group of organs work together it makes an Organism. Organisms can be Unicellular i.e. Amoeba or Multicellular Humans. A cell has different organelles like cell membrane . It is a membranous cover which maintains the intake and outturn of substances. The cell of plants and bacteria are covered by a rigid wall known as Cell wall. The materials inside the cell membrane are a jelly like substance known as cytoplasm with a nucleus. The nucleus consists of the genetic material i.e. the DNA. The nucleus itself consists of jelly like material known as Nucleoplasm and is covered by Nuclear membrane. DNA is in the thread like form known as Chromosome which consists of the genes. Genes are the unit of heredity that is transmitted from one generation to another. Nucleus and the cytoplasm are together known as Protoplasm. The cells also consist of vacuoles which might be small or large depending on the cell type. In some cells an extra circular DNA is present known as Plasmid which can replicate independently. The cells which undergo photosynthesis, like that of plants and some algae, have plastid, which might be of different color. Chlorophyll is the green pigment present in the chloroplast of a plant cell to absorb sunlight for photosynthesis.
There are two types of cells, Prokaryotic cell which are known as primitive cells type like bacteria.
Eukaryotic cells are evolved from the prokaryotic cell, and have advanced organelle functions like plant and animal cells.
Difference between plant and animal cell.
Plant cell | Animal cell |
Plant cell have Cell wall. | Animal cell don’t have Cell wall. |
Plant cell have Plastid. | Animal cell don’t have Plastid. |
Plant cell have large singular vacuoles. | Animal cell have several small vacuoles. |
The protection of plants and animals from the harsh activities of the humans is known as conservation. The process of reckless cutting of trees is known as Deforestation . Building houses, roads, dams, doing cultivation are the reasons of deforestation.
Effects of deforestation:
Flood, as because no trees are present to hold the excess water.
Global warming because plants used CO2 for making food. If lesser plants are there, then there would be less
Intake of the released CO2. CO2, being a greenhouse gas, traps rays of sun and increases the temperature of the earth. It indirectly disturbs the water cycle, which might result in drought.
Plants increase the ground water level which will not be maintained in case of deforestation.
Deforestation causes soil erosion, i.e. washing up of topsoil . It makes the land infertile and barren. This
further causes Desertification.
Government has created different measures to save the plants and animals. Government has created
Wildlife Sanctuaries:
The protected area for plants and animals. Here limited human activities are allowed like collecting of medicinal plants, firewood, etc. Example, Gir wildlife sanctuary in Gujarat, Periyar Wildlife Sanctuary in Kerala.
National Parks:
The protected area for plants and animals where no human activities are allowed. Example
Satpura National Park, Corbett National Park etc.
Biosphere reserves:
Large area for conservation of plants and animals. Here different tribal communities can live and can continue their traditional areas. Example, Nilgiri Biosphere Reserve, Pachmarhi Biosphere Reserve.
The respective plants and animals found in a particular zone of area is known as Flora and Fauna of the
respective zone.
Species are the group of related organisms, which are able to interbreed amongst themselves to produce fertile
offspring.
Plants, animals (Biotic components) along with the climate, air (Abiotic component) of a place make an Ecosystem.
The organisms which are found in a particular area and are rare i.e. not found in other areas, are known as
Endemic species. Example, Kangaroos in Australia.
The animals and plants which are on the way to extinction because of their lesser number, are known as Endangered Species. Example: Black Rhino, Amur Leopard.
Migratory birds cover long distances to lay eggs due to unfavorable conditions in their areas, like scarcity of food, or colder temperature . Example, great grey owl.
The organisms which are no more found in the Earth are called Extinct species. Example, Dodo, Woolly Mammoth.
Red Data Book is the book that maintains the record of the species which are endangered. It is internationally
maintained.
Protect tiger project was an important project to save tigers in India and was started in 1973.
The processes to reduce deforestation are as follows:
Reduce the use of paper and reuse them or recycle them.
More and more number of trees to be planted, this known as Afforestation. When enormous number of trees are
grown to restore a forest, it is known as Reforestation.
CONCEPT: Crop
When a particular variety of plant is grown a particular area, it is known as Crop. The science of cropping
and farming is known as Agriculture.
There are two types of crop divided by the seasons it grows in:
Rabi Crops: Crops that grow during the months of October to March i.e. during the winter season are known
as Rabi Crops. For example, Pea, Mustard, Wheat etc.
Kharif Crops: Crops that are grown in the rainy season i.e. during the months of June- September, are known
as Kharif Crops. For example, Maize, Paddy , Cotton etc.
Further, pulses and vegetables are also grown in summer season.
There are several agricultural practices needed to grow crops properly .Those includes:
Soil preparation
Sowing of seed
Supplying adequate fertilizers and manures
Proper irrigation
Prevention from weeds
Harvesting of crop
Proper storage
CONCEPT: Adding Fertilizers and Manure and Irrigation
Adding Fertilizers and Manure: The natural composts added to the soil to increase the fertility of the soil is known as Manure. Compost is made from natural materials, like crop remains, vegetable peels, human excreta. These are decomposed for months in a closed or open pit and become Compost.
Specific chemical constituents added to the soil to increase its fertility are called fertilizer.
Fertilizers | Manures |
It I These are made in the factories and have chemical Co composition. | It These are made by decomposition of animal and plant wastes. |
It They are rich in Nitrogen, Potassium and Phosphorous. | It I They add minerals to the soil. |
Ex Excess use of it might cause pollution if they get washed A in the nearby water bodies. | N They do not cause any pollution. |
Ex Excess use of it can block the pores of the soil. | It makes the soil loose and rich in microbes. |
Fe It acts rapidly on the soil. | M Manures takes time to give quality result. |
It I Example: NPK, Urea, Ammonium Sulphate. | Example: vegetable peels, human excreta. |
Crop rotation: The process in which altered crops are cultivated in each season is called crop rotation. For example,
If in one summer legumes are grown in some field , the next season it will be replaced by Wheat. This maintains the fertility of the soil.
Irrigation: The process of adding water to the crops is known as irrigation. There are many types of irrigation system:
Pulley system, chain pump, dhekli, and rahat are the older method of irrigation. Wells, ponds, rivers,
` dams and canals are used as the sources of water.
The modern methods include:
Sprinkler System: This system can be used even in lesser water availability. A main pipe is connected to a rotating nozzle at the top. At a regular interval water is sprayed , when water flows through the main pipe under high pressure. It is used for coffee plantation.
Drip System: It is a process in which water is directly supplied to the root of the plant through the pipe. It reduces w loss of water.
CONCEPT: Preparation and Sowing
Soil preparation: The soil is firstly arranged i.e. the soil needs to be loosened and crumbs needs to be broken.
The topsoil, responsible for plant growth, needs to be tilled properly to grow better crops. Sometimes manures
are added using proper devices.
Plough is a device used by the farmers for turning the soil. It has 3 parts beams, which is loaded on the neck of a
Cow or buffalo. Ploughshare is made up of iron, which is the bottom part and foremost responsible for turning the
Soil. Plough shaft is made up of wood joining to the ploughshare. This device requires 2 animals and a human
to drive it. Hoe is a device used by the famers. It is made up of iron and is required to remove weed and loosen
the soil. It has a bent plate, grip, rod , handle, and a beam. Further, the mechanized devices are used like
Cultivator which is attached to a tractor. Tt saves time and labour.
Sowing of seeds: Seeds need to be checked by soaking it in water to reject the damaged floating seed. Tool used in
Sowing of seed is a funnel like device with sharp outlet, to put the seed deeper inside the soil layer.
Further, Seed drill are used now a days to sow seed at a regular depth and distance to prevent the problem of overcrowding of crop.
CONCEPT: Weeding, Harvesting, and Storage
Weeding :The undesirable plant grown along the crop is known as weed. The process of removing weeds from the
field is called weeding. Uprooting of the weeds can be done physically by khurpi, seed drill. It can be done with the help of chemicals known as Weedicide like 2,4-D. Weeds grow along with the normal crop and absorb the nutrients and water from the field. They disturb the growth of desired crops and are harmful.
Harvesting : The process of cutting of the mature crops is known as Harvesting. It can be done manually with the
help of sickle or by a machine known as Harvester. The separation of grains from the chaff is known as Threshing.
A device known as Combine is used to do Harvesting and Threshing all together.
Storage : Storage of grains is done after sun drying it to remove the moisture from it. It is done to protect the crop
from microorganisms. Then the grains are packed in jute bags or metallic containers. Neem leaves , different
chemicals & pesticides are added in the storage rooms to protect the grains from pests and rodents. Silos and
granaries are used to store large scale grains.
The process of rearing animals, i.e. to give them adequate food & shelter for getting agricultural benefits from them is known as Animal Husbandry.
For example, Fish is reared for cod liver oil which is rich in Vitamin D.
CONCEPT: Food Preservation
The chemicals used for the food preservation, are called Preservatives. Sodium benzoate and sodium metabisulphite are the chemical preservatives.
- Sodium chloride is added to meat and fish to limit the growth of microbes in them.
- Sugar reduces the water availability in the jam and jelly and resists the growth of microorganisms.
- Oil makes a layer in pickle, which prevents the outer air to be in contact with the substrates of the pickle.
- Vinegar makes the food acidic to not let greater microbes grow in it.
- Heat kills the remaining microbes in the food. The milk is boiled at 70 degree Celsius for 15-20 minutes to kill the harmful microbes and toxins in the milk, it is known as Pasteurization.
- Lower temperature does not let the microbes to grow in the food.
- If the food is packed in an airtight container to not let the outer air get in the container then the
microbes present outside would not get in and spoil it.
Nitrogen Cycle.
There is 78% of the Nitrogen present in the earth. But the plants cannot use the atmospheric nitrogen. It needs to be converted to Nitrates and nitrites to get absorbed by the plants. The process is known as Nitrogen Fixation. Rhizobium present in the leguminous plants undergo the Nitrogen Fixation in their root. Nitrogen is needed to synthesize proteins, nucleic acids, etc.
When these plants die the Nitrogenous compounds is further converted by the soil microbes into free Nitrogen and released into the free atmosphere. Thus, there is never a reduction of Nitrogen level in the environment.
CONCEPT: Friendly Microorganisms
The organisms that cannot be seen by the naked eye is known as Microorganisms. Fungi, Bacteria, Algae, and Protozoa are the major classifications of microorganisms.
Viruses are minute entities which need host cells for their survival. The host can be a bacteria, a human cell or even
plant cells. Examples of few viruses are , Bacteriophage, TB virus, Dengue virus.
Microbes can be good or bad in use.
Uses of Microorganisms :
- Microbes are used to make curd. The bacteria found in curd is known as Lactobacillus which converts the lactose of the milk into lactic acid. These are also used to make cheese.
- Yeasts are used to make cake, idlis, dosa. Yeast under respiration releases CO2 which makes the dough
fluffy in nature.
- Yeast is also used to make alcohol , this process in known as Fermentation. Fruit extracts, barley, wheat, rice
are used as substrate to undergo fermentation.
- Microbes are also used to make antibiotic i.e. Penicillin is an antibiotic produced by Penicillium notatum. It was first antibiotic discovered by Alexander Fleming, in 1929. This antibiotic kills the harmful microorganism in the body. Streptomycin, tetracycline is the commonly known Antibiotic. It can be used for humans, animals and for even plants pathogens.
- Antibiotics are used against bacterial infections, but viral infections are dealt with Vaccine. Viruses are modified, Killed, and then injected in the human body so that they cannot cause disease. When the body recognizes the vaccine, it makes enough antibodies against the pathogen. When the body is exposed to disease from the specific pathogen next time, it cannot cause infection in the vaccinated individual. TB, Smallpox vaccines are greatly known.
- Microbes are used to degrade the organic wastes and convert them into simpler compound so that plants can
use them. Manures are prepared by this way which increases the fertility of the soil. It also cleans the
environment by decomposing such huge wastes.
CONCEPT: Harmful microorganisms
The microorganisms that causes diseases are known as Pathogenic microorganism.
- Microbes can cause disease in humans, like Vibrio cholera, Plasmodium vivax These microorganisms enter our Body through water , air or food and cause disease . The disease that can be transmitted among the people
around by sneezing or breathing is known as Communicable disease. Example, common cold, chicken pox etc.
Some organisms are responsible for transmitting diseases, i.e. they are responsible for the transfer of pathogen. They are known as Carriers or Vectors. Example female Anopheles mosquito is the vector for the Plasmodium , female Aedes mosquito acts as vector for Dengue virus. These mosquitoes carry the pathogen in their body. When they bite, the pathogen is transferred to the human blood.
Humans need to stay in a clean environment and resist water logging to prevent the breeding of mosquitoes. This is required to get rid of Dengue and Malaria.
- Microbes also cause food poisoning in humans if they eat infected food. Some organisms release toxins
in food. When human consume such food, it may cause dysentery and vomiting like problems. People should always cover the food to prevent such infections.
- Microbes can cause disease in animals too. Anthrax disease is caused by a bacterium which infects both, cattle, and humans. Viruses also causes foot and mouth disease in cattle.
- Plants are also infected by microbes, which affect the growth and yield of the crop. Example, Citrus canker is a
bacterial disease transmitted though air in Orange and Lime plants. Rusts is a fungal disease seen in wheat.
Yellow vein mosaic of Okra is a viral disease. Different chemicals & fungicides are used to resist such infection.
CONCEPT: Adolescence
Adolescence is the period of reproductive maturities. The primary and the secondary sexual character development takes place during this period of life. These change show the onset of puberty.
Development of boys and girls during the age of puberty.
Boys | Girls |
Boys develop deeper voice. | Girls develop sharp voice. |
Boys develop broad chest and shoulder. | Girls develop broad waist. |
Boys develop sperm as male gamete. | Girls develop ovum as female gamete. |
Boys development facial hairs and hairs in chest. | Girls develop breast. |
Testosterone is the male hormone formed. | Girls development estrogen and progesterone hormone. |
The hormones from pituitary initiates the testes and the ovaries to produce the male and female hormones, which further travels through the blood to the target organ. This is known as Endocrine system.
The female hormones are responsible for the menstruation cycle. The production of mature ovum takes place once a month after reaching the age of puberty. This ovum can fuse with sperm to form zygote, which embeds in the uterus.
But if the ovum doesn’t fuse with sperm, its sheds off along with the blood and the walls of the uterus this is known as Menstural cycle, which occurs after every 28-30 days in female. The first menstrual cycle takes place at the onset of Puberty it is called Menarche, and at the age of 45-50 it stops known as Menopause.
The sex of a child is determined by a father and not the mother. Humans have 46 chromosomes ,among them there are 2 sex chromosomes. The female bear XX and the male have XY. Each female gamete has X chromosome in it whereas the male gamete can have either X or Y. The fusion of the female X with X of male gives rise to daughter, whereas the fusion of the female X with Y of male gives rise to son.
There are more hormones i.e. adrenalin secreted by adrenal gland is responsible for fight or flight mechanism of individual. The insulin secreted by pancreas regulate the blood glucose level and the thyroxine hormone secreted by Thyroid gland resists one from Goiter. Many more growth hormones are secreted by the pituitary gland. Meat and fish are rich source of protein. Milk itself are the balanced diet. Banana, jaggery, and meat are the rich source of Iron.
CONCEPT: Reproduction
The process of producing offspring from the parent organism is called reproduction. There are 2 types of reproduction, Sexual reproduction and Asexual reproduction. The process in which two parents, one male and a female are needed to produce a zygote is called Sexual reproduction.
The sperm is the male gamete is made in the male reproductive organ which comprises of a pair of testes, sperm duct and a penis for exclusion. A sperm has a long tail for movement, middle piece and a head. Female reproductive organs include ovaries, fallopian tubes and the uterus. Ovum is the female gamete, which fuses with sperm to produce Zygote. The process of sperm and ovum fusion is known as Fertilization. Fertilization can be of two types, internal and external. In the case of humans, as the zygote develops inside the female body, it is known as Internal fertilization. Each month one ovum matures and comes to the fallopian tube. If it meets sperms. it can form zygote which gets embedded in the uterus and further develops into Foetus i.e. having well differentiated hand legs. Whereas, in the case of frog & fish, the male and the female gametes are laid in the water body during rainy season. The fusion takes place outside the body. It is known as External fertilization.
The development of young ones from the parent organism is known as Viviparous organism, on the other hand when the Organism lays egg this is known as Oviparous organism.
The process of development of organism by drastic changes in the life form is known as Metamorphosis. Example,
Egg → larva or caterpillar → pupa → adult in the case of Silkworm.
The other type of reproduction is called asexual reproduction which takes place only by single parent organism. There are many types of asexual reproduction like binary fission, budding.
When a single cell organism divides into two progeny organism it is known as Binary Fission. It is generally seen in unicellular prokaryotes, bacteria, amoeba, etc.
Budding is a process in which an organism results in the formation of a bulged outgrowth due to the repeated cell division at that site, which further disassociates from the parent organism and results in the formation of fully independent individual. It is generally seen in Hydra, Yeast etc.
