# NEET and AIPMT NEET Botany Principles of Inheritance & Variation MCQ Questions Solved

In human child, sex is determined by

(1) Size and number of sperms in semen

(2) Size of egg to be fertilized

(3) Sex chromosomes of father

(4) Sex chromosomes of mother

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Round seed trait (R) is dominant over wrinkled (r) seed trait in Pea. Heterozygous round seeded plant (Rr) is crossed with wrinkled seed plant (rr). What is the possible progeny?

(1) 302 round : 102 wrinkled

(2) 210 round : 95 wrinkled

(3) 103 round : 99 wrinkled

(4) 103 round : 315 wrinkled

(3) Draw Punnett square as shown in NCERT to get below:

 R r r Rr rr r Rr rr

So, the number of Rr and rr are both 2. Therefore, probability of getting Rr and rr is 1/2. So, the number for Rr and rr should be almost equal in the experiment results.  Option 3 is the only option with almost equal numbers for Rr and rr.

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A dihybrid cross produces the following progeny - AaBb = 240; Aabb =754; aaBb = 746; aabb = 260. What is the distance between the two genes on the chromosome?

(1) 12.5 map units

(2) 1 map unit

(3) 20 map units

(4) 25 map units

(4) Total number of recombinants is 240 + 260 = 500 out of 2000 [240 + 260 + 754 + 746]. This is 25%.

Hint: 1% = 1 map units distance.

Note: It is usually a simple matter to determine which of the gametes are recombinant. These are the gametes that are found in the lowest frequency. AaBb and aabb are recombinant as their frequency is the lowest.

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Male pattern baldness is a          trait

(2) sex-limited

(3) sex-influenced

(3) It is sex influenced. The gene is autosomal and is due to a dominant allele but androgens influence the expression. Thus, a heterozygous male would be bald but not a heterozygous female.

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A colour blind girl is rare because she will be born only when

(1) Her mother and maternal grand father were colour blind

(2) Her father and maternal grand father were colour blind

(3) Her mother is colour blind and father has normal vision

(4) Parents have normal vision but grand parents were colour blind.

(2) The father of a colour blind female must be colour blind. The mother has to be at least a carrier. This is possible if the maternal grandfather was colour blind [remember criss-cross]

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Match each item in COLUMN I with one in COLUMN II and select your answer from the codes given:

 COLUMN I COLUMN II SCIENTIST CONTRIBUTION Francis Crick a. Breaking the genetic code Nirenberg b. Eastablished Coenorthabditis elegans as as a model genetics  study organism Benzer c. Central dogma of molecular biology Brenner d. Bacteriophase genetics
 A B C D (1) c a d b (2) c a B d (3) a b c d (4) a c d B

Francis Crickis is widely known for the use of the term "central dogma" and has also revealed the helical structure of DNA. Nirenberg shared Nobel Prize with Khorana and Holley for deciphering the genetic code. Benzer also described various types of mutations. Brenner focused on establishing Coenorthabditis elegans as a model organism for the investigation of animal development including neural development.

NCERT PAGE 67

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Identify the incorrect statement regarding experiments on Pisum sativum by Gregor Mendel?

(1) He conducted hybridisation experiments on garden peas for seven years (1856-1863) and proposed the laws of inheritance in living organisms.

(2) It was for the first time that statical analysis and mathematical logic were applied to problems in biology.

(3) Unfortunately his experiments had a small sampling size, which gave less credibility to the data that he collected.

(4) He investigated characters in the garden pea plant that were manifested as two opposing traits.

(3) NCERT PAGE 70. The opposite is true. His sample size was large giving larger credibility.

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Which of the following is a recessive trait for a character choosen by Mendel in garden pea?

(1) Violet flower color

(2) Yellow pod color

(3) Axial flower position

(4) tall stem height

(2) NCERT PAGE 71

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Genes which code for a pair of contrasting traits or slightly different forms of the same gene are known as

(1) Alleles

(2) Loci

(3) Cistrons

(4) Introns

(1) NCERT PAGE 72

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Indentify the incorrect statement:

(1) Tall plant produces gametes by meiosis and the dwarf plant by mitosis

(2) Only one allele is transmitted to a gamete.

(3) This segregation of alleles is a random process.

(4) Gametes will always be pure for the trait.

(1) Both produce gametes be meiosis. 4 is true as gametes receive only one allele. NCERT PAGE 73

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