The seven characters of pea plant studied by Mendel are:-
1) Shape of seed (round or wrinkled)

2) Colour of seed (green or yellow)

3) Shape of pod (constricted or inflated)

4) Colour of pod (green or yellow)

5) Colour of the flower (purple or white)

6) Size of the plant (tall or dwarf)

7) Position of the flowers (axial or terminal)

The outer three wall layers perform the function of protection and help in dehiscence of anther to release the pollen.

Tissue matching, blood group matching are essential before undertaking any transplant, otherwise the grafts would be rejected sooner or later. The body is able to differentiate self and non-self and the cell-mediated immune response is responsible for the transplant rejections.

B. Genetic engineering technique is used to modify the genetic material o0f an organism. The organism is called as genetically modified organism. GMO stands for genetically modified organisms. Plants, animals or any other microorganisms which have a new type of genetic material which have been modified through genetic engineering are termed genetically modified organisms. 
There are genetically modified maize plants which can provide more yield when compared to the other field crops. There is production of golden rice which is modified to produce beta-carotene, a form of vitamin A. This prevents vitamin A deficiency and blindness. There are Bt crops which are resistant to pests. 

C. 

The menstrual cycle is a reproductive cycle which takes place in the females of the group of primates. The menstrual cycle is divided into four phases:

(i) Menstrual phase: It extends from 1st to 4th day of the cycle. It occurs in the absence of fertilization. During this phase, bleeding occurs as the endometrium of the uterus is sloughed off. The menstrual flow consists of secretion of endometrial glands, cell debris, unfertilized ovum. After 4th day, once again the FSH secretion from the pituitary is resumed and the new follicle starts developing.

(ii) Follicular phase: When the ovary is in this phase, uterus enters in the proliferative phase. This takes place from 5th to 13th day of the cycle. During this phase new primordial follicle in the ovary develops due to the action of FSH from the pituitary. It gradually changes into Graafian follicle and production of oestrogen starts. Only one follicle develops in one cycle.Corresponding to the changes in the ovary, uterus also undergoes proliferation. Endometrial glands, stimulated by oestrogen do repair process of uterus. 

(iii) Ovulatory phase: During this phase, ovulation takes place. It usually occurs on 14th day. Mature Graafian follicle ruptures due to LH secreted by pituitary. Graafian follicle bursts and releases the ovum. This ovum along with the follicular fluid is picked up by the fimbriae of infundibulum of fallopian tube. It passes through fallopian tube, where, if it happens to meet a sperm, it is fertilized. If not fertilized, the ovum degenerates.

(iv) Luteal phase: It corresponds with the secretory phase in uterus. It takes place between 15th to 28th day of the cycle.

Ovarian changes: In the ovary, corpus luteum is formed from empty Graafian follicle. Progesterone is secreted now. If ovum is fertilized, corpus luteum is retained. LH and LTH from pituitary help in the maintenance of corpus luteum. If ovum is not fertilized, corpus luteum degenerates and forms corpus albicans.

Uterine changes: Under the influence of progesterone, there is increase in the thickness of endometrium. Endometrial glands grow and become secretory. Progesterone is responsible for the maintenance of pregnancy. When fertilized ovum reaches the uterus, it is implanted and placenta is formed. Till placenta becomes functional corpus luteum keeps on producing progesterone. But when progesterone source is cut off, endometrium sloughs off and menstruation begins.

Role of organisms in the nitrogen cycle:

• Bacteria play a central role:
  • Nitrogen-fixing bacteria, which convert atmospheric nitrogen to nitrates.
  • Bacteria of decay, which convert decaying nitrogen waste to ammonia.
  • Nitrifying bacteria, which convert ammonia to nitrates/nitrites.
  • Denitrifying bacteria, which convert nitrates to nitrogen gas.
• Fungi, like bacteria, help to convert dead plants and animals and their wastes into ammonia in the soil.
• Plants absorb nitrates from the soil to make proteins.
• Animals consume plants and use it to form animal protein.
• Humans contribute to the cycle by adding nitrogen rich fertilisers to the soil and by using manure

***-linked inheritance is the appearance of a trait which is due to the presence of an allele exclusively either on X chromosomes or on Y chromosome. Example: Haemophilia. It is X-linked disease. In haemophilia, the sufferer is at a risk of bleeding to death because of the blood either fails or takes time to clot. Usually recessive X bearing males i.e. X'Y and homozygous recessive females X'X' suffer from

haemophilia.

An omnivore is defined as an animal that generally derives its energy and nutrients from a diet of plant and animal matter. Just like carnivores, omnivores hunt prey and other times; they forage for plant matter like herbivores. Humans are classified as omnivores as they eat both animals and plants.
Following are some of the examples of omnivorous animals:

1. Besides humans, many other species live on an omnivorous diet. Some typical mammalian omnivores include racoons which are one of the best examples of an opportunistic feeder. This is because racoons are not very picky and eat anything from mice, frogs, fish, insects, fruits, vegetables to even commercial human wastes such as leftover food.
2. Apart from racoons, other organisms such as opossums, skunks, pigs, rats and most of the bear species are opportunistic feeders. The jerboa is a type of rodent found in the desert that eats plant seeds and insects. The roadrunner is a bird usually found in the desert and its diet composes of fruits and seeds, but animal matter makes up a significant percentage of its diet. These include rodents, insects and even small snakes.
3. Damselfish and parrotfish are omnivores that eat phytoplankton and other smaller fish. There are several omnivorous birds, including chicken, kea, crows, robins, etc. Some reptiles, such as lizards and turtles, are also omnivorous.

The term RNA interference (RNAi) was coined to describe a cellular mechanism that use the gene's own DNA sequence of gene to turn it off, a process that researchers call silencing. ... RNAi is widely used by researchers to silence genes in order to learn something about their function. RNA interference (RNAi) is a post-transcriptional, highly conserved process in eukaryotes that leads to specific gene silencing through degradation of the target mRNA. This mechanism is mediated by double-stranded RNA (dsRNA) that is homologous in sequence to the silenced gene.

Let R = red and r = not red

Rr x Rr (if the male is heterozygous)  yields the genotypes RR Rr, Rr, rr
so there is a 75% chance of having red eyed offspring

Rr x RR (if the male is homozygous) yields the genotypes RR, RR, Rr, Rr
so there is a 100% chance of having red eyed offspring 

...this is calculated using a punnett square, but assumes of course that the gene that codes for red eyes is dominant over genes coding for other eye colours.

It is converted into an active protein (due to alkaline pH of the gut of the boll worm), the toxin binds to midgut cells / create pores / causes cell swelling and lysis that kills the boll worm.

Molecular diagnostics is referred to as the detection of genomic variants, aiming to facilitate detection, diagnosis, subclassification, prognosis, and monitoring response to therapy. Molecular diagnostics is the outcome of the fruitful interplay among laboratory medicine, genomics knowledge, and technology in the field of molecular genetics, especially with significant discoveries in the field of molecular genomic technologies. All these factors contribute to the identification and fine characterization of the genetic basis of inherited diseases which, in turn, is vital for the accurate provision of diagnosis. However, Gene therapy involves the transfer of genetic material, usually in a carrier or vector, and the uptake of the gene into the appropriate cells of the body.

Deleted syllabus of CBSE Class 12 Biology

On July 7, HRD Minister Ramesh Pokhriyal announced a major CBSE syllabus reduction with 30% of the syllabus slashed for the year 2020-21 for classes 9 to 12 because of the reduction in classroom teaching time due to the Covid-19 pandemic and lockdown.

CBSE has rationalized the syllabus with the help of suggestions from NCERT and the same has been notified by a new CBSE notification as well.

The CBSE syllabus has been reduced but care has been taken so that the learning outcomes remain the same and the students do not miss out on learning core concepts in various subjects.

Deleted syllabus of CBSE Class 12 Chemistry

Biotic components are the living things that have a direct or indirect influence on other organisms in an environment. For example plants, animals, and microorganisms and their waste materials.

Abiotic components of an ecosystem include all chemical and physical elements i.e. non-living components. Abiotic components can vary from region to region, from one ecosystem to another. They mainly take up the role of life supporter. They determine and restrict the population growth, number, and diversity of biotic factors in an ecosystem. Hence, they are called limiting factors.

The process is called imprinting. It involves vision, hearing and olfaction along with touch. Just few hours after hatching the chicks use these senses to see the first creature around, usually the mother and bonds. Also movement attracts them and they follow the moving mother all around. 

The thorns or spines of cactus is actually the leaf of the cactus plant.Cactus has undergone adaptation. Usually cactus grown in dry area and there will be more evaporation takes place from leaves .So when leaf is present the water from the cactus plant totally will be get evaporised.Hence to avoid this cactus modified its leaf to thorns. Photosynthesis in cactus take place in the stem of the cactus plant.

Flowers have colorful petals which attract insects. Nectar is produced in petals, stamens, ovaries and other parts of the flower.

Night blooming flowers are generally white because at night they do not have to waste resources to secrete out coloured pigments to be visible to insects and at night white colour refracts light which make them visible for pollination. Pale colored flowers glow in the moonlight, making them easier to find in the dark by pollinators.

Nitrogen fixation is the essential biological process and the initial stage of the nitrogen cycle. In this process, nitrogen in the atmosphere is converted into ammonia (another form of nitrogen) by certain bacterial species like Rhizobium, Azotobacter, etc. and by other natural phenomena.

Plants are the main sources of food. The nutrients obtained from plants are synthesized by plants using various elements which they obtain from the atmosphere as well as from the soil. This group of elements includes nitrogen as well. Plants obtain nitrogen from the soil and utilise in the process of protein synthesis. Unlike carbon dioxide and oxygen, atmospheric nitrogen cannot be obtained through stomata of leaves. Because the nitrogen gas present in the atmosphere can not be directly used by plants. There are certain bacteria and some natural phenomenon which help in Nitrogen fixation.

A breed or strain of animals or plants that maintains a high degree of consistency in certain characters as a result of inbreeding for generations. ... An example of a pure line is the result of inbreeding of a certain flower to help it fight off diseases. Pure-line selection involves selecting and breeding progeny from superior organisms for a number of generations until a pure line of organisms with only the desired characteristics has been established.

F1​ Generation is defined as follow :

F1​ or first filial generation is the generation of hybrids produced from a cross between the genetically different individuals called parents. For example, Tt individuals are produced in F1​ generation from a cross between TT and tt parents.

The phenotypic ratio is 9:3:3:1 whereas the genotypic ratio is 1:2:1:2:4:2:1:2:1.

For example - In a cross between RRYY (round yellow seeds of pea plant) and rryy (green wrinkled seeds of pea plant), all F1 offspring would be RrYy i.e. Round yellow.

Lac operon consists of regulator gene, promoter gene, operational gene and structural gene. The E. coli bacterium carries numerous genes and these genes turn on and off as per requirement. When these genes are turned on, they undergo enzymes which metabolise the new substrate. This phenomenon is known as induction and small molecules eliciting this induction is referred to as inducers. 

In this lac operon, the presence of lactose acts as an inducer. The lac operon contains a promoter, an operator and three closely related structural genes, z, y, a coding for enzymes β-galactosidase, β-galactoside permease and β- galactoside transacetylase respectively. β-galactoside permease pumps lactose into the cells whereas β-galactosidase catalyses the conversion of lactose into glucose and galactose. These genes are not expressed in the absence of lactose. 

The promoter (P) for the operon is the site at which RNA polymerase binds to initiate transcription of the structural genes. The operator (O) is the site at which the protein repressor – the product of regulator gene binds. In the presence of a regulator protein, the RNA polymerase is prevented from attaching to the promoter. A regulator gene is a DNA segment independent of an operon and it synthesizes a repressor protein. This protein combines with an operator and makes it inactive. This prevents RNA polymerase from binding to the adjoining promoter (P) and from initiating transcription of the structural gene. Therefore, RNA polymerase is required to negotiate the operator before transcription can occur. 

The repressor binds to the operator in the absence of a metabolite (effector molecule – lactose). When an inducer or effector molecule-lactose is added to the system, it binds to the repressor to form a complex which is unable to bind the operator. The RNA polymerase enzyme now becomes free to bind with a promoter (P) and so the operator is switched on. This initiates the transcription of structural genes, producing the three polypeptides. These enzymes bring about the metabolism of lactose into glucose and galactose.