What Are Important Diagrams For Class 12 Biology Board Exam PDF Free Download

What Are Important Diagrams For Class 12 Biology Board Exam PDF Download Info

What Are Important Diagrams For Class 12 Biology Board Exam PDF Free Download, कक्षा 12 जीव विज्ञान बोर्ड परीक्षा के लिए महत्वपूर्ण डायग्राम क्या हैं ?

What Are Important Diagrams For Class 12 Biology Board Exam PDF

Biology Is A Crucial Topic For Students In The 12th Grade, Especially For Test Success. The Class 12 Curriculum Includes 16 Chapters In Biology. Included Are The Most Crucial Diagrams From Previous Year’s Test Questions And The Diagrams That Are Most Often Questioned. There Are 13 Diagrammatic Examples Present. Before A Test, Students May Like These Diagrams.

There Are Several Diagrams That Are Important For The Class 12 Biology Board Exam. Here Are Some Of The Key Ones:

• Human Heart: A Labelled Diagram Of The Human Heart, Showing The Different Chambers, Valves, And Blood Vessels.
• Digestive System: A Diagram Of The Digestive System, Including The Mouth, Esophagus, Stomach, Small Intestine, Large Intestine, Rectum, And Anus.
• Photosynthesis: A Labelled Diagram Of The Process Of Photosynthesis, Showing The Structure Of A Chloroplast And The Various Stages Involved.
• Reproductive System: A Diagram Of The Male And Female Reproductive Systems, Including The Structure And Function Of The Different Organs Involved.
• Nervous System: A Diagram Of The Human Nervous System, Including The Brain, Spinal Cord, And Nerves.
• Endocrine System: A Diagram Of The Endocrine System, Showing The Different Glands And Their Hormones.
• Dna Structure: A Labelled Diagram Of The Structure Of Dna, Including The Nucleotide Base Pairs, Sugar-phosphate Backbone, And Double Helix Shape.
• Cell Cycle: A Diagram Of The Different Stages Of The Cell Cycle, Including Interphase, Mitosis, And Cytokinesis.

It Is Important To Practice Drawing And Labelling These Diagrams To Be Well Prepared For The Class 12 Biology Board Exam.

कक्षा 12 जीव विज्ञान बोर्ड परीक्षा के लिए महत्वपूर्ण रचना क्या हैं ?

बोर्ड परीक्षाओं में, एक स्वच्छ, लेबल वाला ग्राफ़िक बनाने से आपको अंक प्राप्त करने में मदद मिल सकती है। एक आरेख अधिक उपयोगी है और प्रभावी ढंग से जानकारी देता है। एक छवि अधिक संवाद कर सकती है। यहां आपके लिए कक्षा 12 की बोर्ड परीक्षाओं के अध्ययन के लिए कुछ महत्वपूर्ण डायग्राम दिए गए हैं।

यहां आपको 2020 सीबीएसई कक्षा 12 जीव विज्ञान बोर्ड टेस्ट के लिए महत्वपूर्ण आरेख मिल सकते हैं। कक्षा 12 जीव विज्ञान एनसीईआरटी पाठ्यपुस्तकों से आरेख-आधारित प्रश्न बोर्ड परीक्षाओं में लगातार प्रस्तुत किए गए हैं। इस वर्ष के लिए सीबीएसई कक्षा 12 जीव विज्ञान बोर्ड टेस्ट 14 मार्च, 2020 को निर्धारित किया गया है।

यदि आप हाल ही में कक्षा 12 के जीव विज्ञान के सैंपल पेपर (सीबीएसई द्वारा जारी) को देखते हैं, तो आप देखेंगे कि कई प्रश्न एनसीईआरटी पाठ्यपुस्तकों के आरेखों और आलेखों पर आधारित हैं।

ऐसे कई डायग्राम हैं जो कक्षा 12 जीव विज्ञान बोर्ड परीक्षा के लिए महत्वपूर्ण हैं। यहाँ कुछ प्रमुख हैं:

• मानव हृदय: मानव हृदय का एक नामांकित आरेख, विभिन्न कक्षों, वाल्वों और रक्त वाहिकाओं को दर्शाता है।
• पाचन तंत्र: मुंह, अन्नप्रणाली, पेट, छोटी आंत, बड़ी आंत, मलाशय और गुदा सहित पाचन तंत्र का आरेख।
• प्रकाश संश्लेषण: प्रकाश संश्लेषण की प्रक्रिया का एक नामांकित आरेख, एक क्लोरोप्लास्ट की संरचना और इसमें शामिल विभिन्न चरणों को दर्शाता है।
• प्रजनन प्रणाली: पुरुष और महिला प्रजनन प्रणाली का एक आरेख, जिसमें शामिल विभिन्न अंगों की संरचना और कार्य शामिल हैं।
• तंत्रिका तंत्र: मानव तंत्रिका तंत्र का आरेख, जिसमें मस्तिष्क, रीढ़ की हड्डी और तंत्रिकाएं शामिल हैं।
• एंडोक्राइन सिस्टम: एंडोक्राइन सिस्टम का एक आरेख, विभिन्न ग्रंथियों और उनके हार्मोन को दर्शाता है।
• डीएनए संरचना: डीएनए की संरचना का एक लेबल वाला आरेख, जिसमें न्यूक्लियोटाइड बेस जोड़े, चीनी-फॉस्फेट बैकबोन और डबल हेलिक्स आकार शामिल हैं।
• कोशिका चक्र: कोशिका चक्र के विभिन्न चरणों का एक आरेख, जिसमें इंटरपेज़, माइटोसिस और साइटोकिनेसिस शामिल हैं।

कक्षा 12 जीव विज्ञान बोर्ड परीक्षा के लिए अच्छी तरह से तैयार होने के लिए इन आरेखों को बनाने और लेबल करने का अभ्यास करना महत्वपूर्ण है।

All Important Diagrams For Class 12 Biology Board Exam

Male Reproductive System

The male reproductive system consists of the following:

• Primary sex organ: testes.
• Secondary or accessory sex organs:

1. Accessory ducts: rete testis, vasa efferentia, epididymis, and vas deferens.
2. Accessory glands: seminal vesicle, prostate, and bulbourethral glands (Cowper’s gland).

• External genitalia: penis.

Female Reproductive System

The female reproductive system consists of the following:

• Primary sex organ: ovary
• Secondary sex organs:

1. Accessory ducts: pair of oviducts (fallopian tubes), uterus, cervix, and vagina.
2. Accessory gland: mammary gland.

• External genitalia: vulva.

Mammary gland

• The human female has a pair of mammary glands (breasts) that contain glandular tissues and fatty tissues.
• Each glandular tissue is divided into 15-20 mammary lobes and each lobe consists of a group of alveoli.
• The alveoli open into mammary tubules.
• The mammary tubules of each lobe open into small mammary duct.
• Several mammary ducts join to form a wider mammary ampulla that is connected to lactiferous duct just before the nipple through which milk is released.

Human Sperm

• The sperm consists of four parts — head, neck, middle piece, and tail.
• A plasma membrane envelops the whole body of the sperm.
• The Head is the enlarged end of a sperm, contains an elongated haploid nucleus, the anterior portion of the nucleus capped by the acrosome.
• The neck contains proximal centriole which is necessary for the first cleavage division of the zygote and the distal centriole that is connected to the tail filament.
• Middle piece contains a number of mitochondria that provide energy for the movement of the tail.
• The tail consists of axial filaments surrounded by the plasma membrane. It helps the sperms to swim in a fluid medium.

Section of Young Anther

A typical microsporangium appears circular in outline and is surrounded by four walls:

1. Epidermis: It is the outermost single layer of cell which is protective in nature.
2. Endothecium: It is the second layer with thick cells, helps in dehiscence, and is protective in nature.
3. Middle layer: It is the third layer composed of 1-3 layers of cells, helps in dehiscence, and is protective in nature.
4. Tapetum: It is the fourth and innermost layer of cell with dense cytoplasm and many nuclei. It provides nourishment to the developing pollen grains.

Anatropous ovule 

• The ovule is a small structure attached to the placenta by means of a stalk called a funicle.
• The junction between an ovule and a funicle is called the hilum.
• The ovule is surrounded by one or two protective envelopes called integuments.
• Integument encircles the ovule entirely except at the tip, resulting in a small opening called the micropyle.
• The basal part of an ovule opposite to micropyle is called chalaza.
• The cells with high or abundant reserve food material enclosed within the integument is called nucellus.
• The female gametophyte located within the nucellus is called an embryo sac.

An Embryo Sac

• The female gametophyte (embryo sac) develops from a single functional megaspore.​
• This megaspore undergoes three successive mitotic divisions to form eight nucleate embryo sacs.
• At the micropylar end, out of the four nuclei only three differentiate into two synergids and one egg cell. Together they are known as the egg apparatus.
• Similarly, at the chalazal end, three out of four nuclei differentiate as antipodal cells.
• The remaining two cells (of the micropylar and the chalazal end) move towards the centre and are known as the polar nuclei, which are situated in a large central cell.
• Hence, at maturity, the female gametophyte appears as a 7-celled structure, though it has 8 nucleate.

Spermatogenesis

Spermatogenesis is a process in which diploid spermatogonia undergo meiosis to produce haploid spermatids.

• Each spermatogonium (2n) present within the seminiferous tubules undergoes mitotic division, resultant cells are called primary spermatocytes (2n).
• These primary spermatocytes periodically undergo meiosis and produce two equal, haploid cells called secondary spermatocytes (n), which have only 23 chromosomes each.
• The secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids (n).
• The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis.

Oogenesis

The process of formation of a mature haploid female gamete from the diploid oogonium is called oogenesis.

• Oogonia undergo meiosis and enters prophase-I, and get temporarily arrested at the stage called primary oocytes.
• Each primary oocyte then gets surrounded by a layer of granulosa cells and then called the primary follicle.
• The primary follicles get surrounded by more layers of granulosa cells and a new theca and called secondary follicles.
• The primary oocyte within the tertiary follicle undergoes first meiotic division resulting in the formation of a large haploid secondary oocyte and a tiny first polar body.
• Secondary oocyte undergoes second meiotic division to produce a haploid ovum (n) with a second polar body.

Dihybrid Cross

The cross between two homozygous individuals differing in two characters is called dihybrid cross.

• Mendel crossed true-breeding round yellow-coloured seeds (RRYY) with wrinkle green coloured seeds (rryy).
• The gametes RY and ry unite on fertilisation to produce the F1 hybrid RrYy.
• Mendel found that the seeds resulting from the crossing of the parents had round shaped yellow coloured seeds (RrYy) in the F1 generation.
• In the next step, F1 hybrids were self-pollinated.
• In the F2 generation 9 Round, yellow: 3 Wrinkled, yellow: 3 Round, green: 1 Wrinkle, green seeds are produced.
• The phenotypic ratio of the dihybrid cross is 9:3:3:1.

Incomplete Dominance

It’s a phenomenon in which the F1 hybrid exhibits intermediate characters of the parental gene.

• It is seen in flower colours of Mirabilis jalapa (4 O’clock plant and Antirrhinus majus (Snapdragon).
• In a cross between true breeding red flowered (RR) and true breeding white flowered plants (rr), the F1 (Rr) was pink.
• When the F1 was selfpollinated the F2 resulted in the following ratio 1 Red (RR) : 2 Pink (Rr) : 1 White (rr).
• Here the phenotypic ratio deviates from the Mendel’s monohybrid cross.
• Both phenotypic and genotypic ratio will be the same 1:2:1.

Nucleosome

• The negatively charged DNA is wrapped around the positively charged histone octomere to form a structure called a nucleosome.
• A typical nucleosome contains 200 bp of DNA helix.
• Nucleosomes constitute the repeating unit of a structure in the nucleus called chromatin, a thread-like stained bodies seen in the nucleus.
• The nucleosomes in chromatin are seen as ‘beads-on-string’ structure under electron microscope.
• Histones are organised to form a unit of eight molecules called histone octomere.

Replicating Fork

• The unique and fixed point where the DNA replication originate is called ‘origin of replication’ or ‘ori’.
• The complementary strands of DNA double helix are separated by DNA helicase and DNA gyrase. This process is called unwinding of double stranded DNA.
• The unwinding of double-stranded DNA forms a ‘Y-shaped’ configuration in the DNA duplex, which is called the replication fork.

Transcriptional Unit

The transcription unit of DNA contains three regions in the DNA:

1. The promoter: It is the binding site for RNA polymerase for initiation of transcription.
2. The structural gene: It codes for enzymes or protein for structural functions.
3. The terminator: It is the region where transcription ends.​

lac Operon Concept

• In the absence of inducer (Lactose): The regulator gene i regulates and produces repressor protein. The repressor protein binds to the operator region of the operon and prevents RNA polymerase from transcribing the operon. Hence, no enzymes are formed. This type of operon is said to be “Switched off”.
• In the presence of inducer: Lactose as an inducer, binds to the repressor and repressor becomes inactive. Now the repressor fails to bind to the operator region. This allows RNA polymerase binds to the operator and transcribes lac mRNA. Lac mRNA is polycistronic, produces all three enzymes called β-galactosidase, permease, and transacetylase. Now the operon is termed as “Switched on”.

Miller’s Experiment

S L Miller and H C Urey performed an experiment in 1953 for chemical evolution.

He created electric discharge in a closed flask containing CH4, H2, NH3 and water vapours at 800 oC.

After few weeks he observed the formation of amino acids and complex molecules like sugars, nitrogen bases, pigments and fats in the flask.

Conclusions:

• It provides experimental evidence for the theory of chemical origin.
• It showed that the first non-cellular form of life was created about 3 billion years ago.
• It showed that non-cellular biomolecules exist in the form of DNA, RNA, polysaccharides and proteins. Formation of first cell first non-cellular.

An Antibody Molecule

Antibodies are protein molecules called immunoglobulins (Ig) and are of five typesIgA, IgM, IgE, IgG, and IgD.

An antibody has a Y-shaped structure.

Each antibody molecule consists of four polypeptide chains, two are long called heavy (H) chains while the other two are short called light (L) chains. Hence, an antibody is represented as H2L2.

IgG is the most prevalent antibody in the blood followed by IgA and IgM.

IgA is present in breast milk (colostrum).

Biogas Plant

• The raw material for biogas production is the excreta (dung) of cattle.
• The biogas plant has a concrete tank (10-15 feet deep) in which bio-wastes and slurry of dung are collected.
• The tank has a floating cover, which keeps on rising on the production of gas in the tank.
• Methanobacterium in the dung act on the bio-wastes to produce biogas.
• The gas produced is supplied to nearby houses by an outlet.
• Through another outlet, the spent slurry is removed to be used as fertiliser.
• Biogas is used as fuel for cooking and lighting.

Bioreactor

Bioreactors are vessels of large volumes (100-1000 liters) in which raw materials are biologically converted into specific products.

• It provides all the optimal conditions for achieving the desired product by providing optimal growth conditions like temperature, pH, substrate, salt, vitamins, and oxygen.
• Stirred-tank bioreactors are commonly used bioreactors.
• These are cylindrical with a curved base to facilitate proper mixing of the contents.

Agarose Gel Electrophoresis

Gel electrophoresis is a technique for separating DNA fragments based on their size and net electric charges.

​

pBR322

pBR322 is the first artificial cloning vector developed in 1977 by Boliver and Rodriguez from E. coli plasmid.

A cloning vector ha the following features;

• Origin of replication (ori)
• Selectable markers
• Cloning site

Life-cyle of Retrovirus (HIV)

• After getting into the body of a person, the virus enters the macrophages.
• Here, RNA is replicated to form viral DNA by enzyme reverse transcriptase.
• The viral DNA now gets incorporated into the host cell’s DNA and directs the infected cells to produce viruses.
• The virus particles enter helper T-lymphocytes (TH cells) in the blood, where they continue to replicate and produce viral progenies.

Life-cyle of Plasmodium vivax

• Plasmodium requires two hosts to complete its cycle – Mosquito and human.
• The infected female Anopheles mosquito transfers the infectious form of Plasmodium, i.e., sporozoites to the human body by biting.
• The sporozoites reach the liver cells, where they multiply.
• This is followed by their attack on red blood cells resulting in their rupture.
• ​The ruptured RBCs release a toxin called haemozoin, which is responsible for high recurring fever, chills, and shivering.
• These parasites enter the female Anopheles mosquitoes when they bite an infected person.
• In the body of mosquitoes, they fertilize and multiply in the stomach wall.
• Sporozoites are now stored in the salivary gland of mosquito till it is again transferred to the human body by a mosquito bite. After entering the human body, all the events are repeated.​