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

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

Relaxin

Human Chorionic Gonadotropin

Oxytocin

Human Placental Lactogen

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:

You know that there are twenty different types of naturally occurring amino acids and four different types of bases in the DNA. A combination of 3 such bases code for a specific amino acid. If instead there are 96 different amino acids and 12 different bases in the DNA, then the minimum number of combination of bases required to form a codon is ______.

6

8

2

4

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

Hydrogen bond

Peptide bond

N-glycosidic linkage

Phosphodiester bond

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

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

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 improved trait that is found in the genetically modified transgenic crop - Golden rice is ______.

High lysine content

Insect resistant

High protein content

High vitamin-A content

The rate of formation of new organic matter by consumers, and the biomass available for consumption of herbivores as well as decomposers are referred to as ______.

Gross primary productivity and Net primary productivity

Net primary productivity and Secondary productivity

Secondary productivity and Net primary productivity

Secondary productivity and Gross primary productivity

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 (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): 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.

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

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. 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.

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.

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.

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)

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

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.

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.

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.

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)

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.

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.

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.