Biology 57/1/3 2023-2024 Science (English Medium) Class 12 Question Paper Solution

Refer to the Venn diagram given below. Select the option with correct examples P, Q, and R: 

The type of bond represented by the dotted line '------' in a schematic polynucleotide chain is ______.

Hydrogen bond

Peptide bond

N-glycosidic linkage

Phosphodiester bond

Lactobacillus that sets milk into curd is categorised as ______.

Cyanobacteria

Archaebacteria

Chemosynthetic bacteria

Heterotrophic bacteria

Which one of the following transgenic animals is being used to test the safety of the polio vaccine?

Sheep

Goat

Pig

Mice

The scientist who proposed that "embryos of all vertebrates including humans develop a row of vestigial gill slits behind the head but it is a functional organ only in fish and replaced by lungs in all other vertebrates" is ______.

Darwin

Lamarck

Ernst Haeckel

Mendel

Which one of the following hormones is secreted by the human placenta that helps in the maintenance of pregnancy?

Relaxin

Human Chorionic Gonadotropin

Oxytocin

Human Placental Lactogen

During an allergic reaction, the binding of antigen to IgE antibodies initiates release of ______.

Interferon

Histamine

Heparin

Acetylamine

Select the incorrect match from the following:

Restriction Endonuclease - Hind II always cuts DNA molecules at a particular point by recognising a specific sequence of ______.

Six base pairs

Four base pairs

Seven base pairs

Three base pairs

The periodic abstinence by a couple for family planning should be from ______.

Day 5 to 10 of menstrual cycle

Day 13 to 15 of menstrual cycle

Day 10 to 17 of menstrual cycle

Day 16 to 20 of menstrual cycle

Which one of the following bacteria were used by Stanley Cohen and Herbert Boyer to accomplish the construction of the first rDNA?

Agrobacterium tumefaciens

Mycobacterium sp.

E. coli

Salmonella typhimurium

The organism that occupies more than one trophic level in a pond ecosystem is ______.

Fish

Frog

Zooplankton

Phytoplankton

Assertion (A): Indian Government has set up an organisation known as GEAC to decide the validity of GM research.

Reason (R): Genetic modification of organisms has no effect when such organisms are introduced in the ecosystem.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Assertion (A): Gene flow increases genetic variations.

Reason (R): The random introduction of new alleles into a recipient population and their removal from donor population affects allele frequency.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Assertion (A): The laws of our country permit legal adoption and it is as yet, one of the best methods for childless couples looking for parenthood.

Reason (R): Emotional, religious and social factors are no deterrents to the legal adoption of orphaned and destitute children in India.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Assertion (A): Agrobacterium tumefaciens is a pathogen of several monocot plants.

Reason (R): It is able to deliver a piece of DNA known as 'T-DNA' to transform normal plant cells into a tumor.

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

Assertion (A) is true, but Reason (R) is false.

Assertion (A) is false, but Reason (R) is true.

Study the diagram of a pyramid of biomass given below. Name the two standing crops that could be occupying level 'A' and level 'B in it. Name this type of pyramid and the ecosystem in which it is found.

Given below is an illustration of the experiment performed by Louis Pasteur. Explain the experiment and its conclusion.

Identify A, B, C and D in the table given below:

"Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used." Support this statement with the help of two suitable examples.

Identify A, B, C and D in the following table:

Write the basic steps followed in the Assisted Reproductive Technologies (ART) programme to help childless couples.

Why Assisted Reproductive Technologies (ART) is also known as test tube baby programme?

1. Explain the significance of the experiment carried out by S.L. Miller. Name the scientists whose hypothesis prompted him to carry out this experiment.    (2.5)
2. How does meteorite analysis favour this hypothesis?    (0.5)

1. Identify the picture given below and name the tool under which it was viewed.   [1]
   
2. What do the dark spots represent in the picture? Explain how and why are they formed.   [2]

In a family, the father, the daughter and the son are colour blind, whereas the mother has normal vision. Do you think the son and the daughter have inherited the disease from their father? Work out a cross to justify your answer.

Identify A and B in the diagram below. Explain their role in the immune system of the body.

1. Explain how it is ensured that the orchid Ophrys is pollinated by a specific species of bee.
2. Describe co-evolution with the help of this example.

Explain the mode of action of contraceptive pills taken by human females. 

A woman has certain queries as listed below, before starting with contraceptive pills. Answer them.

What schedule should be followed for taking these pills?

What are transgenic animals?

Name the first transgenic cow and state its importance.

Explain the convention for naming EcoRI.

With the help of an illustration only, show the action of EcoRI on a DNA Polynucleotide.

Read the following passage and answer the questions that follow.

(a) Why is the species richness maximum in Region III in the bar graph?   (1)

                                              OR

(a) Why is the species richness minimum in Region I in the bar graph?   (1)

(b) Plants and animals do not have uniform diversity in the world but show rather uneven distribution. Mention what this kind of diversity is referred to as.   (1)

(c) Why is it that prokaryotes do not have an estimated number of their species diversity as seen in plants and animals? Explain.   (2)

Study the diagram given below that shows the steps involved in the procedure of selecting transformed bacteria and answer the questions that follow:

(a) Identify the colony that has got transformed. Justify your answer.   (0.5 + 0.5)

(b) What are the sites in a plasmid called where ampicillin and tetracycline resistance genes are inserted? State their role in genetic engineering.   (2)

(c) Name two enzymes playing an important role in genetic engineering.   (1)

                                             OR

(c) State the role of β-galactosidase in insertional inactivation.   (1)

Draw a labelled diagram of the embryonic stage that gets implanted in the human female leading to pregnancy.

Explain the changes that the different parts of the embryo undergo after implantation up till placenta formation.

Explain the changes that the different parts of the embryo undergo after implantation up till formation of three germ layers.

Write the role of placenta in pregnancy.

Mention the role of the following:

Three germ layers

Why do plants like Viola and Oxalis give assured seed sets even in the absence of pollinators? When an orange seed is squeezed, many embryos of different shapes and sizes are observed. Why?

Mention four advantages of seed formation to angiosperms.

Draw a diagram of the mature embryo sac of an angiospermic ovule and label any four parts in it.

Name and explain the property present in normal cells but is lost in cancer cells.

All normal human cells have genes that may become cancerous under certain conditions. Name them and explain how.

State the role of the following techniques in detection and diagnosis of cancer:

Biopsy and Histopathology

State the role of the following techniques in detection and diagnosis of cancer:

Magnetic Resonance Imaging

Study the flow diagram and answer the questions that follow:

1.   
   1. Why is primary effluent passed into large aeration tanks?   [1]
   2. What is the 'sediment' formed, referred to as? Mention its significance.   [1]
   3. Explain the final step in the settling tank before the treated effluent is released into water bodies.   [1]
2. Name any two organisms commonly used as biofertilisers, belonging to different kingdoms. Write how each one acts as a biofertiliser.   [2]
3. Many patterns of inheritance deviate considerably from the pattern of inheritance as explained by Mendel. List any four such inheritance patterns and explain any three with the help of an example each.

Stability, as one of the properties of genetic material, was very evident in one of the very early experiments in genetics. Name the scientist and describe his experiment. State the conclusion he arrived at.

A tall pea plant bearing violet flowers with unknown genotype is given. Find the genotype by working out different crosses only by selfing the plants. Write the genotypic and phenotypic ratios of each cross shown by you.