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Class 12 Biology Answer Key 2021 Term 1
CBSE Class 12 Biology Answer Key Term 1 2021: Central Board of Secondary Education is conducting the Class 12th Biology exam for Term 1 on 18th December 2021. The time of examination is 11:30 am to 1:00 pm, which means the board has allotted 90 minutes to solve the question paper of biology. With question paper, the students will get an OMR sheet to fill their responses, in the OMR sheet the students have to fill in some important information except their responses. The important information includes the name of the student, roll number of the student, question paper set number, question paper code, etc. In this article, we have provided the CBSE Class 12 Biology Answer Key Term 1 2021, the answer key is prepared by the expert faculty of ADDA247 and will be available within one hour after completion of the examination. We have provided the CBSE Class 12 Biology Answer Key Term 1 2021 on our youtube channel too. Hence, the visually impaired students can also evaluate their score by using the CBSE Class 12 Biology Answer Key Term 1 2021 provided on youtube.
Check: Class 12 History Answer Key 2021
Class 12 Biology Answer Key Term 1 2021
According to new guidelines announced by the Central Board of Secondary Education, the students have to enter the examination center at 10:45 am i.e. 45 minutes early from the exam time. Before starting the exam, students will get extra 20 minutes to read the question paper, although the OMR sheet to fill responses will be distributed to students on time of the exam i.e. 11:30 am. The students must bring the admit card to them to the exam center and must follow the covid guidelines written on the admit card.
Check: Class 12 All Subjects Answer Key 2021
Class 12th Biology Answer Key Term 1 2021
Paper Code: 057/2/4
Please Refresh the page to get updated answers
| 1(c) | 2(b) | c(d) | 4 (a) | 5 (a) | 6(d) |
| 7(c) | 8(d) | 9(d) | 10(c) | 11(b) | 12(a) |
| 13(b) | 14(b) | 15(a) | 16(b) | 17(d) | 18(b) |
| 19(a) | 20(c) | 21(c) | 22(b) | 23(c) | 24(a) |
| 25(a) | 26(c) | 27(a) | 28(b) | 29(b) | 30(a) |
| 31(d) | 32(a) | 33(c) | 34(d) | 35(d) | 36(d) |
| 37(c) | 38(b) | 39(a) | 40(c) | 41(c) | 42(c) |
| 43(b) | 44() | 45(d) | 46(b) | 47(b) | 48(a) |
| 49(b) | 50(c) | 51(a) | 52(b) | 53(d) | 54(a) |
| 55(c) | 56(c) | 57(d) | 58(d) | 59(b) | 60(b) |
Paper Code: 057/3/4
Please Refresh the page to get updated answers
| 1(a) | 2(a) | 3(c) | 4(c) | 5(b) | 6(d) | 7(b) | 8(c) | 9(c) | 10(c) |
| 11(c) | 12(b) | 13(c) | 14(b) | 15(c) | 16(b) | 17(d) | 18(c) | 19(d) | 20(c) |
| 21(c) | 22(b) | 23(a) | 24(c) | 25(b) | 26(a) | 27(d) | 28(b) | 29(d) | 30(c) |
| 31(d) | 32(c) | 33(d) | 34(b) | 35(c) | 36(b) | 37(c) | 38(d) | 39(b) | 40(b) |
| 41(c) | 42(a) | 43(b) | 44() | 45(b) | 46(a) | 47(c) | 48(d) | 49(a) | 50(a) |
| 51(c) | 52(a) | 53(a) | 54(b) | 55(b) | 56(b) | 57(a) | 58(c) | 59(d) | 60(b) |
Paper Code: 057/1/4
Please Refresh the page to get updated answers
| 1(b) | 2(c) | 3(a) | 4(c) | 5(c) | 6(b) | 7(c) | 8(b) | 9(c) | 10(d) |
| 11(d) | 12(d) | 13(a) | 14(c) | 15(c) | 16(c) | 17(b) | 18(b) | 19(a) | 20(a) |
| 21(b) | 22() | 23(d) | 24(d) | 25(a) | 26(d) | 27(d) | 28(c) | 29(c) | 30(b) |
| 31(c) | 32(c) | 33(b) | 34(c) | 35(a) | 36(c) | 37(b) | 38(b) | 39(c) | 40(d) |
| 41(b) | 42(a) | 43(b) | 44() | 45(b) | 46(c) | 47(d) | 48(c) | 49(a) | 50(c) |
| 51(a) | 52(a) | 53(b) | 54(b) | 55() | 56(a) | 57(c) | 58(c) | 59(a) | 60(c) |
Class 12 Biology Official Answer Key Term 1 2021
Biology Class 12 Questions Paper Term 1 2021
Paper Code 057/2/4
Paper Code 057/3/4
Paper Code 057/1/4
CBSE Class 12 Biology Term 1 Answer Key 2021: Questions and Answers
Q. Life cycle of Drosophila melanogaster is completed in –
(a) 7 days
b) 14 days
(c) 21 days
(d) 28 days
Answer- (b)
Q. How many types of gametes would develop by an organism with genotype?
(a) 1
(b) 2
(c) 3
(d) 4
Answer- (d)
Q. Given below are the observations drawn in HGP. Select the option that shows the correct observations.
(i) The human genome contains 3164.7 billion base pairs.com
(ii) The average gene consists of 3000 bases.com
(iii) Less than 2% of the genome codes for proteins.
(iv) Chromosome one has most genes (2698) .
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)
Answer- (b)
Q. The phosphoester linkage in the formation of a nucleotide involves the bonding between
(a) Phosphate group and OH of 3’C of a nucleoside
(b) Phosphate group and OH of 5’C of a nucleoside
(c) Phosphate group and H of 3’C of a nucleoside
(d) Phosphate group and H of 5’C of a nucleoside
Answer- (a)
Q. The switching ‘on’ and ‘off of the lac operon in prokaryotes is regulated by
(a) Glucose
(b) Galactose
(c) Lactose
(d) Fructose
Answer- (c)
Q. For ‘in-vitro’ DNA replication, which one of the following substrates need to be added along with the necessary enzymes, the DNA template and specific conditions?
(a) Ribonucleotide triphosphate
(b) Deoxyribonucleoside triphosphate
(c) Deoxyribonucleotide triphosphate
(d) Ribonucleoside triphosphate
Answer- (c)
Q. Which one of the following factor will associate transiently with RNA polymerase to terminate transcription in prokaryotes?
(a) sigma factors
(b) RHO factor
(c) delta factor
(d) theta factor
Answer- (b)
Q. Choose the correct pair of codon with its corresponding amino acid from the following list :
(a) UAG: Glycine
(b) AUG : Arginine
(c) UUU: Phenylalanine
(d) UGA: Methionine
Answer- (Answer- (b))
Q. During the elongation process of translation, the peptide bond formation between amino acids is catalysed by –
(a) ribosomal RNA
(b) protein in the small subunit of the ribosome
(c) protein in the large subunit of the ribosome
(d) transfer RNA
Answer- (a)
Questions consists of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below :
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b). Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
Q. Assertion (A): Through Reproductive and Child Health (RCH) programmes in India, we could bring down the population growth rate.
Reason (R): A rapid increase in MMR and IMR were the reasons, along with other reasons for this.
Answer- (a)
Q. Assertion (A): Sterilisation methods are generally advised for a male partner as a terminal method to prevent any more pregnancies.
Reason (R): These techniques are less effective and have high reversibility.
Answer- (c)
Q. Assertion (A): The inner cell mass of the blastocyst gets attached to the endometrium during embryonic development in humans,
Reason (R): The blastomeres in the blastocyst gets arranged into trophoblast and inner cell mass.
Answer- (a)
Q. Assertion (A): There is an expression of only one gene of the parental character in a Mendelian Monohybrid cross in Fi generation.
Reason (R): In a dissimilar pair of factors one member of the pair dominates the other
Answer- (b)
Q. Select the correct option for Human Chorionic Gonadotropin (HCG) released during embryonic development in humans.
(i) Helps in the maintenance of pregnancy.
(ii) Leads to rupture of Graafian follicle.
(iii) Cause strong uterine contraction during childbirth.
(iv) Brings metabolic changes in the mother.
(a) (i) and (ii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
Answer- (b)
Q. Residual persistent nucellus in black pepper is known as
(a) Perisperm
(b) Pericarp
(c) Pulvinus
(d) Perianth
Answer- (a)
Q. The hilum in a typical angiospermic ovule represents the junction between –
(a) Integuments and the embryo sac.
(b) Embryo sac and the nucellus
(c) Body of the ovule and the funicle
(d) Nucellus and the funicle
Answer- (c)
Q. In the given diagram of a transverse section of a young anther. Choose the labellings showing the correct placement of the wall layers from the table given below:
| Option | (i) | (ii) | (iii) | (iv) |
| (a) | Epidermis | Middle layers | Tapetum | Endothecium |
| (b) | Tapetum | Endothecium | Epidermis | Middle layers |
| (c) | Endothecium | Tapetum | Middle layers | Epidermis |
| (d) | Middle layers | Epidermis | Endothecium | Tapetum |
Answer- (b)
Q. The term used for the embryo entering into the state of inactivity as the seed mature is –
(a) Quiescent
(b) Parthenogenesis
(c) Parthenocarpy
(d) Dormancy
Answer- (d)
Q. The ploidy of the apomictic embryo developed from the integument cells and megaspore mother cell without reduction division respectively will be –
(a) 2n and 2n
(b) n and n
(c) 2n and n
(d) 3n and 2n
Answer- (a)
Q. Given below is a diagrammatic representation of a mature embryo sac of a typical angiosperm plant. Choose the option showing the correct labellings for the parts W, X, Y and Z from the table given below.
| Option | (i) | (ii) | (iii) | (iv) |
| (a) | Microplyar End | Antipodals | Synergids | Central Cells |
| (b) | Chahazal Ends | Antipodals | Central Cells | Synergids |
| (c) | Microplyar End | Synergids | Central Cells | Antipodals |
| (d) | Chahazal Ends | Synergids | Central Cells | Antipodals |
Answer- (a)
Q. Breast-feeding the baby acts as a natural contraceptive for the natural contraceptive for the mother because it prevents :
(i) Ovulation C
(ii) Menstruation
(iii) Insemination
(iv) Fertilisation Choose the correct option:
(a) (ii) and (iv)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i) an (ii)
Answer- (d)
Q. During human embryonic development, the external genital organs are well developed in the foetus by the end of
(a) 6 weeks of pregnancy
(b) 12 weeks of pregnancy
(c) 18 weeks of pregnancy
(d) 24 weeks of pregnancy
Answer- (b)
Q. The accessory ducts in the human male reproductive system consists of –
(a) Epididymis, Prostrate, Rete testis
(b) Rete testis, Vas efferentia, Seminal vesicles
(c) Vas efferentia, Bulbourethral, Epididymis
(d) Rete testis, epididymis, Vas deferens
Answer- (d)
Q. An undifferentiated sheath covering the root cap of a monocotyledonous embryo is –
(a) Scutellum
(b) Coleorhiza
(c) Coleoptile
(d) Epiblast
Answer- (d)
Q. The cause of Down’s syndrome in humans is :
(a) Extra copy of an autosome
(b) Extra copy of a sex chromosome
(c) Absence of an autosome
(d) Absence of a sex chromosome
Answer- (a)
Q Which of the following features show the mechanism of sex determination in honey-bee?
(i) An offspring formed from the union of a sperm and egg develops as a male.
(ii) Males have half the number of chromosomes than that of female.
(iii) The females are diploid having 32 chromosomes.
(iv) Males have father and can produce sons.
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Answer- (b)
Q. Select the pair that is incorrect :
(a) Sickle-cell anemia : Autosome linked recessive trait
(b) Haemophilia : Autosome linked recessive trait
(c), Colour blindness : Sex linked recessive trait
(d) Thalassemia : Autosome linked recessive traita
Answer- (b)
Q. An example of a human trait where a single gene can exhibit multiple phenotypic expressions is –
(a) Phenyl ketonuria
(b) Cystic fibrosis
(c) Thalassemia
(d) Haemophilia
Answer- (a)
CBSE Class 12 Biology Exam Pattern
CBSE has divided the Class 12th Term 1 biology question paper into three sections i.e. A, B, and C. The board will be asked an overall 60 questions of which 50 questions are mandatory to attempt. In the Class 12th Term 1 biology examination, objective-type questions will be asked. There is no provision for negative marking so students can guess the answers to those questions which they find difficult or unable to find the answer to. The following A, B, and C sections are given below:
- Section A: Section A contains 24 questions in which the students can attempt any of the 20 questions.
- Section B: Section B contains 24 questions in which the students can attempt any of the 20 questions.
- Section C: Section C contains 12 questions in which the students can attempt any of the 10 questions.
| Section | Questions | Compulsory to Attempt |
| Section A | 24 | 20 |
| Section B | 24 | 20 |
| Section C | 12 | 10 |
Upcoming Answer Keys of CBSE Class 12th Exam
In the below table we have given the list of coming exam dates with subjects. The students will get the answer keys for all the coming exam papers, so students are advised to bookmark this page if they are appearing in CBSE Class 12th examination.
| Date | Subject |
| 20th December 2021 | History |
| 21st December 2021 | Informatics Prac, Computer Science |
| 22nd December 2021 | Home Science |
CBSE Class 12th Biology Syllabus for Term 1
Here we have given the CBSE Class 12th Biology Syllabus for Term 1, the questions in today’s biology paper will be asked from Reproduction and Genetics and Evolution. The students must check the CBSE Class 12th Biology Syllabus for Term 1 given below in the table.
| Units | Marks |
| Reproduction(Chapter – 2, 3, and 4) | 15 |
| Genetics and Evolution(Chapter – 5 and 6) | 20 |
| Practical Examination | 15 |
| Total Marks | 50 |
CBSE Class 12th Biology Examination Timings
The students are required to report to the exam center at 10:45 am, the late comers will be properly screened at the examination center. Before the starting of the examination, the students will get 20 minutes to read the question paper. Check the other exam timings in the table given below:
| Reporting Time | 10:45 Am |
| Question Paper Reading Time | 20 minutes |
| Exam Start Time | 11:30 Am |
| Exam End Time | 1:00 Pm |
CBSE Class 12th Examination Guidelines
The students appearing in the Term 1 examination of Class 12th must follow the CBSE guidelines.
- The students are required to carry hall tickets with them to the examination center.
- The students must follow the covid guidelines given on the admit cards.
- The use of pencil on OMR sheet is prohibited so students must carry a blue or black pen to fill the OMR sheet.
- According to the new way of response filling, the students must write their answers in capital letters, the CBSE has issued a circular on 7th December 2021 to inform students about this new method. Earlier the students were allowed to fill responses in small letters.
- The students must fill all the information and response on the OMR sheet neatly so it will be easy for evaluators to evaluate the OMR sheet.
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FAQs on CBSE Class 12 Biology Answer Key Term 1 2021
Q. Where can I get Biology Class 12 Answer Key Term 1?
We have provided the Class 12 Biology Answer Key 2021 for Term 1 on this page. The students can use Class 12 Biology Answer Key 2021 for Term 1 to calculate the marks.
Q. What is the level of Biology Class 12 Term 1?
The level of Biology Class 12 Term 1 is easy to moderate.
Q. Will CBSE release the official Biology Class 12 Answer Key 2021-22?
The Central Board of Secondary Education has not been informed yet about the official Class 12 Biology Answer Key 2021 for Term 1. Whenever CBSE uploads Class 12 Biology Answer Key 2021 for Term 1 on its official website we will update the same here.
Q. When will CBSE announce the result of the Class 12 Term 1 examination?
After completion of the Class 12th Term 1 examination, CBSE will announce the result.
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