Biology 57/1/2 2023-2024 Science (English Medium) Class 12 Question Paper Solution

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

Hydrogen bond

Peptide bond

N-glycosidic linkage

Phosphodiester bond

Select the option that has the correct sequence of events of human female reproductive cycle:

1. Secretion of FSH
2. Ovulation
3. Growth of corpus luteum
4. Growth of follicle and oogenesis
5. Sudden increase in LH

i - iii - v - iv - ii

i - iv - v - ii - iii

iv - i - v - iii - ii

v - ii - iii - iv - i

Lactobacillus that sets milk into curd is categorised as ______.

Cyanobacteria

Archaebacteria

Chemosynthetic bacteria

Heterotrophic bacteria

The specific Bt toxin genes which protect the cotton plants against the cotton bollworms are ______.

Cry-I Ac and Cry-II Ab

Cry-I Ab and Cry-I Bc

Cry-II Ac and Cry-I Ac

Cry-II Ab and Cry-I Ab

Listed below are some amino acids and their corresponding mRNA codons: 

Select the DNA sequence that would code for the following polypeptide sequence:

Polypeptide: Alanine - Arginine - Lysine - Phenylalanine

CGT GCT TTC AAA

CGT GCT TTC TTT

CGU GCU UUC AAA

CGU GCU UUC TTT

In which of the following plants are both male and female flowers born on the same plant and the mode of pollination can be geitonogamy or xenogamy?

Papaya

Date Palm

Maize

Spinach

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

Sheep

Goat

Pig

Mice

In which of the following conditions/diseases is there a substantial increase in the activity of mast cells observed in the human body?

Typhoid

Allergy

Ascariasis

AIDS

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

Select the incorrect match from the following:

Using a DNA template, how many new DNA molecules would be generated after 10 cycles of amplification in PCR?

512

1024

2048

256

Read the four statements given below and select the option having two correct statements: 

1. A lion eating a deer and a sparrow feeding on grains are ecologically similar in being consumers.
2. Predator starfish Pisaster helps in maintaining species diversity of some invertebrates.
3. Predators ultimately lead to extinction of prey species.
4. Production of chemicals nicotine and strychnine by plants are metabolic disorders.

i and iii

ii and iv

i and ii

iii and iv

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.

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): Linked genes do not show dihybrid F₂ ratio 9 : 3 : 3 : 1.

Reason (R): Linked genes do not undergo independent assortment.

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: Functional ADA cDNA genes must be inserted in the lymphocytes at the early embryonic stage.

Reason: Cells in the embryonic stage are mortal, differentiated and easy to manipulate.

Both A and R are true and R is the correct explanation of A.

Both A and R are true and R is not the correct explanation of A.

A is true but R is false.

A is False but R is true.

Do you think apomixis can be compared to asexual reproduction? Justify your answer.

State the benefits of apomixis to the farmers.

1. What did the doctor inject and why?   (1.5)
2. Name the kind of immunity provided by this injection.   (0.5)

Why do organic farmers not recommend complete eradication of insect pests? Explain giving reason.

Observe the picture given below. Name the naturalist and write the explanation given by him that evolution of life forms had occurred on the basis of this example.

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. Name the plant that was introduced into Australia and mention the reason for its uncontrollable growth.
2. State how its spread was eventually brought under control.

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.

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

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?

Name and write two characteristics of the type of DNA that forms the basis of DNA fingerprinting technique.

Give the applications of DNA fingerprinting technique.

Given below is a picture that shows the magnified blood smear of a patient under a microscope.

1. Name the disease the blood smear is indicative of. Write the symptoms of the disease and its cause.    (1)
2. Explain the inheritance pattern of the disease with the help of a suitable cross.    (2)

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)

State what is primary productivity and mention its units.

Some ecologists observed that primary productivity of a place in Rajasthan was low as compared to a particular place in Kerala. Explain why.

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)

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)

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.

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.

Construct a transcription unit with a coding strand given below with proper labelling:

When does a coding strand become a template strand?

Why does a double-helix DNA molecule transcribe into a single-stranded RNA molecule?

Explain the development of male gametophyte in angiosperms (diagram is not expected).

Draw a labelled diagram of a three-celled male gametophyte.

Draw a diagrammatic sectional view of ovary of human female and label the following:

1. Blood vessels
2. Primary follicle
3. Tertiary follicle
4. Ovum

At which stage of life are primary follicles formed in a human female?

Explain the events (both hormonal and structural) that occur at the time of ovulation till the onset of the next menstrual cycle.