NIOS Solved TMA 2023 Class 12 Biology

Biology (314)
Tutor Marked Assignment

Max. Marks: 20

Note:

• All questions are compulsory. The marks allowed for each question are given at same place
• Write your name enrollment numbers, AI name, and subject on the top of the first page of the answer sheet.

1. Answer any one of the following questions in about 40-60 words:



(a) Explain the term differential reproduction in two steps

\[Ans:\] Differential reproduction means that individuals with a certain genotype for a given locus or gene have more reproductive success than individuals within the same population with another genotype for that same gene. This difference in reproductive success can be the result of longer survival that results in more reproductive events over a lifetime, more offspring per reproductive event, or more frequent successful reproductive events.
Differential reproduction is the idea that those organisms best adapted to a given environment will be most likely to survive to reproductive age and have offspring of their own.

2. Answer any one of the following questions in about 40-60 words:



(b) Why does a cell remain stable when placed in isotonic solution? What happens to it if placed in a hypotonic solution?

\[Ans:\] The solution has two components, solute, and solvent. Solute is the substance, which is dissolved in a Solvent. The solute is always less in quantity than solvent. For e.g. Salt (a solute) is dissolved in water (a solvent), to make a solution.
The cell remains stable when placed in an isotonic solution because that contains the same concentration of water and solutes as the cell cytoplasm is called isotonic solutions. Cells placed in an isotonic solution will neither shrink nor swell since there is no net gain or loss of water.
A hypotonic solution has less solute concentration and more solvent concentration. When a cell is placed in a hypotonic solution, water enters the cell through endo osmosis. Plant cells swell up and become turgid. Animal cells swell and burst due to the absence of cell wall.


3. Answer any one of the following questions in about 40-60 words:



(i) You ate a meal comprising pulses (dal) and chapatis (roti). In which parts of the digestive system would their digestion begin, and be completed?
(ii) Also name the end products.

\[Ans: \] Chapati digestion begins in the mouth. The enzyme present in the saliva (amylase) initiates the breakdown of complex carbohydrates into sugars. Once this is swallowed, it goes down the oesophagus into the stomach (where the mushing happens) into the duodenum and from there to the small intestine. The big chunk of carbohydrate digestion happens here. The pancreatic amylase breaks polysaccharides to disaccharides in the duodenum. Then, the enzymes lactase, sucrase, and maltase break this down to monosaccharides in the small intestine which is are absorbed. So the chapati you’re eating gets digested from complex carbs to simple sugars in the mouth and intestine.
Digestion of protein: Proteins are made of amino acids, during its digestion protein decomposes and gets converted into amino acid.
There is no enzyme present for digestion of protein in saliva so protein is digested in stomach. Digestion of protein in stomach: Stomach generally stores food for 4-5 hours gastrin gland secretes gastric juice. It possesses HCI, inactive enzymes, pepsinogen and renin.
Protein breakdown begins within the stomach. An enzyme within the juice of the stomach starts the digestion of swallowed protein. Protein digestion within the stomach occurs mainly by the action of hydrochloric acid (HCl) and an enzyme called pepsin. The chyme first enters the duodenum, which is a part of the small intestine.
Further digestion of the protein is completed within the small intestine. Here in Duodenum several enzymes from the digestive juice and therefore the lining of the intestine perform the breakdown of giant protein molecules into small molecules called amino acids. In the ileum, these small molecules are often absorbed from the hollow of the small intestine into the blood then carried to all or any parts of the body.

(ii) Also name the end products.
The end product of protein digestion is amino acids. Protein is broken down by various proteolytic enzymes in the stomach and duodenum such as pepsin, trypsin, chymotrypsin, dipeptidase, exopeptidase, etc.
The final product of carbohydrate digestion is monosaccharides such as glucose, galactose, fructose, etc.


4. Answer any one of the following questions in about 100-150 words:



(i) Describe the role of thin, and thick muscle fibres in the contraction of a striated muscle as explained by the sliding filament theory.
(ii) All tissues of plants require Nitrogen?

\[Ans:\] The myofibrils are made up of thick and thin myofilaments, which help give the muscle its striped appearance. The thick filaments are composed of myosin, and the thin filaments are predominantly actin, along with two other muscle proteins, tropomyosin, and troponin. Muscular contraction is caused by the interaction between actin and myosin as they temporarily bind to each other and are released.
The mechanism of muscle contraction is best explained by the sliding filament theory which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments. Muscle contraction is initiated by a signal sent by the central nervous system (CNS) via a motor neuron.
A motor neuron along with the muscle fibers connected to it constitute a motor unit. The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate.
A neural signal reaching this junction releases a neurotransmitter (Acetylcholine) which generates an action potential in the sarcolemma. This spreads through the muscle fiber and causes the release of calcium ions into the sarcoplasm.
The process continues till the Ca++ ions are pumped back to the sarcoplasmic cisternae resulting in the masking of actin filaments. This causes the return of ‘Z’ lines back to their original position, i.e., relaxation. The reaction time of the fibres can vary in different muscles.
ii) All tissues of plants require Nitrogen.
Nitrogen is required by all part of the plant, particularly the meristematic tissues and metabolically active cells.
Nitrogen is one of the essential macroelements present in plants. It is one of the nonmineral elements. Plants absorb nitrogen from the soil as nitrate. Nitrogen is required in the largest amount in plants. It is mainly required in the meristematic tissues and metabolically active cells. It is present in large number of biomolecules, so it is essential for plants.


5. Answer any one of the following questions in about 100-150 words:



(i) Draw a sigmoid growth curve of a plant to show lag phase, log phase and stationary phase. Mention what happens to a plant during these phases.
(ii) Some wheat and rice varieties are kept at a lower temperature to flower in the same climate. Define this process.

\[Ans: \] The rate of growth of a plant or plant part is not always the same during its life span. Sometimes it is slow and at other times rapid. If we plot the increase in cell number (growth rate) against time, a typical S-shaped curve is obtained. This is called growth curve or sigmoid growth curve.
This curve has three phases of growth.
Lag Phase – This is the initial phase of growth when the rate of growth is very slow.
Log Phase – It shows rapid growth and is maximum during the entire life span.
Stationary Phase – Here the rate of growth starts decreasing and finally it stops.


Sigmoid growth curve

The total time period during which the fastest growth of the organ or organism occurs is called grand period of growth.
(ii) Some wheat and rice varieties are kept at a lower temperature to flower in the same climate. Define this process.
In the process of vernalization, flowering is facilitated by a cold treatment provided to a completely hydrated seed or to a growing plant. As a result of the process of vernalization, the vegetative phase of the plant is restricted, which leads to early flowering. In the absence of cold treatment, those plants which need vernalization exhibit delayed flowering or stay vegetative.
if temperature is reduced to a particular point then flowering occurs at an early stage. For example by applying a temperature ranging between 1-10° C to certain variety of wheat, rice and cotton, growth of seedlings is accelerated and flowering occurs earlier. This method of inducing early flowering in plants at low temperatures is called vernalization.


6. Prepare any one of the project out of two given below.

(b) Take photographs (or draw Portrait or write name) of one of your parents or siblings and yourself. Stick them close to each other. Now below each photograph enter the following:


	Inherited Feature	Father/Mother/Brother/Sister	Yourself
1	Whether can roll tongue	Yes/No	Yes/No
2	Whether can flex thumb backwards
3	Whether earlobe free or fixed

Write down the following
i. What is genetics? Write the meaning of inheritance
ii. Draw a Pedigree Chart to show inheritance of any of the characters studied in you and your siblings.
iii. Comment on whether you got the gene from the father or mother, and write a sentence as an evidence for the same.


Name of Common disease	Name of Patient (Get from the clinic or patient)	Age	Symptoms	Causative Organism	Mode of Transmission
1
2

I. What is genetics? Write the meaning of inheritance
It can be defined as the passing of genetic information from parents to their offspring or progeny or the next generation. The similarity in features of one generation with the other generation is an example of heredity. Heredity is also termed as an inheritance. Inheritance is the process by which genetic information is passed on from parent to child.
II. Draw a Pedigree Chart to show inheritance of any of the characters studied in you and your siblings.
Creating Your Pedigree: 3 Steps
Ask questions, write down what they say, collect all information possible
Draw a basic outline of your family tree using pedigree symbols
Record the information you gathered on the drawing to complete the pedigree

Family pedigree only for example please don’t copy it… (Make your own)
III. Comment on whether you got the gene from the father or mother, and write a sentence as an evidence for the same.