Maharashtra board class 12 students who will be taking one of the most important exam of their life, Board Examination 2019, would be stressed under the exam preparations and revising the vast syllabus of class 12. Here the best way to minimize the burden of study and make an effective preparation for exams, solving the previous years’ question papers. It is considered to be the best practice to not only familiarising with the pattern of questions asked in board examinations but also to analyse your preparation level and strong/weak areas. Previous years’ board question papers serve as a perfect tool to get an idea about the important questions and topics covered in the board examinations which can further help students to brief their study content.
In this article, we are providing the Maharashtra Board Class 12 Biology Solved Question Paper 2018. Solutions have been collated in the form of PDF which students may download to check the right criteria to write perfect exam and score high marks in Maharashtra board HSC board exam 2019.
Key features of Maharashtra Board Class 12 Biology Solved Question Paper 2018 are
- Simple and detailed solutions are provided for each question
- Appropriate concepts/theories have been used in solutions
- Neat and labelled diagrams are used wherever required
A few sample questions and their solutions are given below:
Q. What is leaching?
It is a process where the water soluble nutrients go down into the soil layers and get locked as unavailable salts.
Q. Enlist the basic steps involved in recombinant DNA technology.
Given below are the basic steps involved in recombinant DNA technology:
- Identification and isolation of gene of interest
- Joining of this gene into a suitable vector (construction of recombinant DNA)
- Introduction of this vector into a suitable organism
- Selection of transformed recombinant cells with gene of interest
- Multiplication or expression of the gene of interest
Q. Describe different steps involved in tissue culture technique.
There are three main steps involved in tissue culture technique, which are described below:
(i) Explant culture: Proper explant is excised from the plant which may be a cell, tissue or a piece of the plant organ. Generally, parenchyma tissue or meristem is used as explants. The cells from explant absorb nutrients and start multiplying to form callus. Callus is the unorganised mass of cells.
(ii) Sterilization: In tissue culture technique, different apparatus, the medium used and the explant also is to be properly sterilized to avoid the contamination due to which the experiment may fail. The methods used for sterilization may be dry or wet sterilization, Alcohol sterilization etc. The explants used can be sterilized by using 1% sodium hypochlorite or 70% ethyl alcohol or 10% hydrogen peroxide.
(iii) Organogenesis: Now the growth hormones like auxins and cytokinins in proper proportion are provided to the callus to induce the formation of organs. If auxins are more, roots are formed (rhizogenesis) and if the cytokinins are in more quantity then the shoot system begins to develop (caulogenesis).
Q. State any ‘two’ symptoms of Down’s syndrome.
Symptoms of Down syndrome as observed in children are as follows: (any two)
- Face tends to be round and flat with small and low-set nose.
- The nose may be small with a flat and low bridge.
- The back of the head (called the occiput) is slightly flattened.
- Eyes slant upwards and have an extra fold of skin (epicanthic fold) on the upper eyelid. This skin fold covers the inner corner of the eye.
- Mental retardation
Q. Describe the histology of ‘human testis’.
The testis are retroperitoneal from the time of development, until they descend into their final adult position in the scrotum. The testes hang in suspension attached to the spermatic cord and are covered externally by the loose, wrinkly, pigmented skin known as the scrotum. Just inside the scrotum, there are three more distinguishable layers that protect the testicular tissue.
(i) Tunica vaginalis: It is the outermost incomplete peritoneal covering made up of connective tissue and
(ii) Tunica albuginea: It is the middle layer formed by fibrous connective tissue.
(iii) Tunica vasculosa: It is the innermost layer formed of delicate connective tissue, supporting a network of blood capillaries.
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