By QB365 on 31 Dec, 2022
QB365 provides a detailed and simple solution for every Possible Questions in Class 12 Biology Subject - Important 2 Mark English Medium. It will help Students to get more practice questions, Students can Practice these question papers in addition to score best marks.
12th Standard
Biology
Answer all the following questions.
Why is the offspring formed by asexual reproduction referred as a clone?
What is inhibin? State its functions
Differentiate foeticide and infanticide
What are holandric genes?
Name the parts marked ‘A’ and ‘B’ in the given transcription unit:
Mention the main objections to Darwinism.
Autoimmunity is a misdirected immune response. Justify.
List the advantages of biogas plants in rural areas.
PCR is a useful tool for early diagnosis of an Infectious disease. Elaborate
What is soil permeability?
What are the three levels of biodiversity?
What effect can fertilizer runoff have on an aquatic ecosystem?
What are clones?
Define Genetics.
From the above figure identify the type of mutation and explain it.
What are the materials used to grow microorganism like Spirulina?
What is the name of the process given below? Write its 4 types.
What is Phytoremediation ?
Pyramid of energy is always upright. Give reasons
Expand CCS. (or) What is CCS?
Differentiate between primary introduction from secondary introduction.
Name the humors that are responsible for the health of human beings.
How does immune system work?
Identify the parts marked as A, B, C, D and E for the below diagram.
In females a oogonia forms a single ovum only. What is the significance of the oogonia undergoing meiosis I & II when in a male, each spematogonia forms 4 sperms .
Define Tubectomy and Vascetomy.
Write the possible genotypes for a person having B-blood group
What are the two major components of prokaryotic RNA polymerase? How do they act?
List out the two main propositions of oparin and Haldane.
Name two plants with hallucinogenic properties.
Answers
Offsprings produced by asexual reproduction are called clones, because they are genetically as well as morphologically similar to the parent organism.
They are not only similar to one another, but are also exact copies of their parent (e,g): Amoeba, Spirogyra, Hydra, Yeast, etc.
In testes Sertoli cells secrete inhibin, a hormone which is involved in the negative feedback control of sperm production. (Spermatogenesis).
Foeticide | Infanticide |
It refers to aborting the female in the mother's womb. |
It refers to killing the female child after her birth |
The genes present in the differential region of Y chromosome are called Y- linked or holandric genes. The Y linked genes have no corresponding allele on X chromosome. The Y linked genes inherit along with Y chromosome and they are phenotypically express only in the male sex.
A - \(5^{\prime} \rightarrow 3^{\prime}\) is called a coding strand.
B - \(3^{\prime} \rightarrow 5^{\prime}\) is called a template strand.
(i) Darwin failed to explain the mechanism of variation.
(ii) Darwinism explains the survival of the fittest but not the arrival of the fittest.
(iii) He focused on small fluctuating variations that are mostly non-heritable.
(iv) He did not distinguish between somatic and germinal variations.
(v) He could not explain the occurrence of vestigial organs, over specialization of some organs like large tusks in extinct mammoths, oversized antlers in the extinct Irish deer, etc.,
Autoimmunity is due to an abnormal immune response in which the immune system fails to properly distinguish between self and non-self and attacks its own body. Our body produces antibodies (autoantibodies) and cytotoxic T cells that destroy our own tissues. If disease-state results, it is referred to as auto-immune disease.
Thus, autoimmunity is a misdirected immune response. Eg., Rheumatoid arthritis and multiple scleroids
(i) Biogas is a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen.
(ii) The slurry is drained through another outlet and is used as fertilizer.
(iii) Biogas is used for cooking and lighting.
(i) PCR is a very sensitive technique which enables the amplification of desired DNA from a limited amount of DNA template.
(ii) A technique can be also used for amplifications of RNA in which case it is referred to as reverse transcription PCR (RT-PCR). In this process the RNA molecules (mRNA) must be converted to complementary DNA by the enzyme reverse transcriptase (reverse transcription).
(iii) The cDNA then serves as the template for PCR.
(iv) The specificity and sensitivity of PCR is useful for the diagnosis of inherited disorders (genetic, viral; bacterial, diseases).
(v) Hence, it can detect the presence of an infectious organism in the infected patient at an early stage of infection (even before the infectious organism has multiplied into large number).
1. The characteristic of soil that determines the movement of water through pore spaces is known as soil permeability.
2. Soil permeability is directly dependent on the pore size. Water holding capacity of the soil is inversely dependent on soil porosity.
There are three levels of biodiversity are
(1) Genetic diversity
(2) Species diversity and
(3) Community / Ecosystem diversity
1. Fertilizer runoff degrades aquatic eco system by promoting growth of algae, phytoplankton's and other aquatic plants.
2. A phenomenon called algal bloom will take place, by increasing oxygen consuming bacteria and lessening the available oxygen for plants and animals in the area.
3. Depletion of fish special general deterioration of water quality are the serious problems in aquatic eco system.
Individuals formed by asexual reproductive methods are morphologically and genitically identical and are called clones.
"Genetics" is the branch of biological science which deals with the mechanism of transmission of characters from parents to off springs.
(i) A type of structural chromosomal abrevation.
Reverse tandem duplication
(ii) The duplicated segment is located immediately after the normal segment but the gene sequence order will be reversed.
Spirulina can be grown easily on materials like waste water from potato processing plants (containing starch), straw, molasses, animal manure and even sewage, to produce large quantities.
Name of the process-Plant tissue culture Types:
(a) Organ culture
(b) Meristem culture
(c) Protoplast culture
(d) Cell culture
Certain plants can also be used to remove cadmium from contaminated soil, this is known as phytoremediation.
Example: Eichhornia
There is a gradual decrease in energy transfer at successive tropic levels from producers to higher levels, hence the pyramid of energy is always upright.
CSS - Carbon Capture and Storage.
Primary Introduction | Secondary Introduction |
(i) No alternation of genes | (i) Alternation by hybridizdtion |
(ii) Adaptation capability is more | (ii) Adaptation capability is more after hybridization |
Vatam, Pittam and Kapam.
The immune responses may be primary or secondary.
(i) The primary immune response occurs when a pathogen comes in contact with the immune system for the first time.
(ii) The secondary immune response occurs when a person is exposed to the same antigen again. During this time, immunological memory has been established and the immune system can start producing antibodies immediately. Within hours after recognition of the antigen, a new army of plasma cells are generated. Within 2 to 3 days, the antibody concentration in the blood rises steeply to reach much higher level than primary response. This is also called as "booster response".
A - Monaxon spicules
B - Micropyle
C - Outer membrane
D - Archaeocytes
E - Inner membrane
The meiotic divisions I & II take place in order to ensure that the ovum is haploid since normal chromosomal number is important for formation of normal zygote. Further polar bodies have less cellular contents and are small since they do not participate in fertilization most of the cellular contents lie in the ovum.
(i) Tubectomy is the surgical sterilisation method in women.
(ii) Vasectomy is the surgical sterilisation method in male.
The possible genotypes of a B-blood group person are IBIBor IBlO.
Bacterial (prokaryotic) RNA polymerase consists of two major components, the core enzyme and the sigma subunit. The core enzyme (\({ \beta }^{ 1 },\beta \) and \(\alpha\)) is responsible for RNA synthesis whereas a sigma subunit is responsible for recognition of the promoter.
(i) The first form of life could have come from pre-existing non-living organic molecules like RNA, proteins etc.
(ii) Formation of life was preceeded by chemical evolution that resulted in the formation of diverse organic molecules from inorganic constituents.
Atropa belladona and Datura