Tag: incomplete dominance

Questions Related to incomplete dominance

A red snapdragon flower is crossed with a white snapdragon flower, and all the resulting flowers from the cross are pink. Which type of inheritance is occurring here? 

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Incomplete dominance

  2. Codominance

  3. Sex-linked inheritance

  4. Pleiotropy

  5. Polygenic inheritance

Show answer
Correct Option: A
Explanation:
A. When F1 hybrid exhibit a mixture or blending of characters of two parents, it is called incomplete dominance. For example, in snapdragon one parent is homozygous for red flowers (AA) and the other is homozygous for white flowers (aa). No dominance is present and the heterozygous F1 flowers are pink. The 1: 2: 1 ratio of red, pink and white flowers in the F2 progeny is shown by appropriate colouring.
B. In codominance, both alleles of a pair express themselves fully in F1 hybrid. For example, in cattles when a cattle with red coat is crossed with the cattle having white coat, the F1 hybrid possess roan appearance. In roan appearance, the red and white hairs occur in patches but no hairs have intermediate colour of red and white.
C. Sex chromosomes are primarily concerned with the determination of sex, but these do carry the genes also for other characters. Such characters whose genes are located on the sex chromosomes are known as sex-linked characters. The genes which govern these sex-linked characters are known as sex-linked genes and their inheritance is known as sex-linked inheritance. For example, colour blindness in humans.
D. Pleiotropy is the condition in which one gene produces many effects. In other words, a pleiotropic gene produces a major phenotypic trait and also, it influences some other phenotypic traits.
E. Polygenic inheritance is the condition when many genes control the inheritance of one trait or character. Such genes are called polygenes and show quantitative inheritance. For example, kernel colour of wheat and skin colour in humans.
So, the correct answer is 'Incomplete dominance'.

Incomplete dominance is also called

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Intermediate inheritance

  2. Blending inheritance

  3. Partial dominance

  4. All the above

Show answer
Correct Option: A

Mendel did not propose

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Dominance

  2. Incomplete dominance

  3. Segregation

  4. Independent assortment

Show answer
Correct Option: B
Explanation:

A.Law of dominance – When two contrasting alleles for a character come together in an organism, only one is expressed and another one is not expressed. Expressed character is called Dominant character and the character which is not expressed is called Recessive character

B.Incomplete dominance – Expression of new phenotypes in the progeny, other than the parents is called Incomplete dominance

C.Segregation – This law states both parental alleles of F1 generation separate and are expressed phenotypically in F2 generation

D.Independent assortment – When a cross is made between two individuals different from each other in two or more characters, then the inheritance of one character is independence of the inheritance of another character

So, the correct answer is ‘Incomplete dominance’

Phenotypic and genotypic ratio in $F _2$ generation in incomplete dominance is

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. 1 : 2 : 1 and 1 : 2 : 1

  2. 3 : 1 and 1 : 2 : 1

  3. 9 : 6 and 3 : 1

  4. 9 : 3 : 3 : 1 and 1 : 2 : 1 : 4 : 1 : 1 : 2 : 1 : 2 : 1.

Show answer
Correct Option: A
Explanation:

Appearance of new phenotypes or intermediate phenotypes, other than parental phenotypes in progeny  is incomplete dominance. In this, In the F2 generation, 1 red flowered plants(RR), two pink flowered plants(Rr), 1 white flowered plants(rr) are formed. So, the phenotypic and genotypic ratio is 1:2:1.

So, the correct option is ‘1:2:1 and 1:2:1’.

A plant having 24 cm long internodes is crossed with a plant having 12 cm long internodes. The hybrids have 18 cm long internodes due to

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Multiple allelism

  2. Complete dominance

  3. Recessive dominance

  4. Incomplete dominance

Show answer
Correct Option: D
Explanation:

Appearance of new phenotypes or intermediate phenotypes, other than parental phenotypes in progeny  is incomplete dominance. A plant having  24cm long internodes is crossed with plant having 12cm long internodes. In the hybrids 18cm long internodes appear. It is due to blending of characters. So, it is called Incomplete dominance or blending inheritance.

So, the correct option is ‘Incomplete dominance’.

Which one is exception to Mendel's principle of dominance?

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Wild Pea

  2. Mirabilis

  3. Garden Pea

  4. Maize

Show answer
Correct Option: B
Explanation:

Gregor Johann Mendel, an Austrian Monk, discovered the principles of heredity through the experiments on the pea plant. Mendel conducted hybridization experiments on garden peas for seven years and proposed the laws of inheritance in living organisms. They are Law of dominance, Law of segregation, Law of Independent assortment. These laws are exceptional in some cases like incomplete dominance, co-dominance, etc.

So, the correct option is ‘Mirabilis’.

$F 2$ generation has genotypic and phenotypic ratio 1 : 2 : 1. It is _______________.

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Codominance

  2. Dihybrid cross

  3. Monohybrid cross with complete dominance

  4. Monohybrid cross with incomplete dominance.

Show answer
Correct Option: D
Explanation:

A.Codominance – Phenotypic and genotypic ratio is 1:2:1

B.Dihybrid cross – Phenotypic ratio is 9:3:3:1 and genotypic ratio is 1:2:2:4:1:2:1:2:1

C.Monohybrid cross with complete dominance – phenotypic ratio is 3:1 and genotypic ratio is 1:2:1

D.Monohybrid cross with incomplete dominance - Phenotypic and genotypic ratio is 1:2:1

So, the correct option is ‘Codominance & Monohybrid cross with incomplete dominance’.

In Antirrhinum (dog flower), phenotypic ratio in $F _2$ generation for the inheritance of flower colour would be

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. 3:1

  2. 1:2:1

  3. 1:1

  4. 2:1

Show answer
Correct Option: B
Explanation:

The inheritance of flower colour in the Antirrhinum majus (snapdragon or dog flower) is an example of incomplete or partial dominance. Incompleted dominance is the phenomenon in which neither of the two alleles of a gene is completely dominant over the other. In a cross between true-breeding red-flowered (RR) and true-breeding white-flowered plants (rr), the $F _1$ plants obtained were pink (Rr) coloured. When the $F _1$ plants were self-pollinated, the $F _2$ generation resulted in the ratio, 1 (RR) Red :2 (Rr) Pink: 1 (rr) White. The phenotypic ratios had changed from the normal 3 : 1 dominant : recessive ratio to 1: 2: 1. R was not completely dominant over rand  this made it possible to distinguish Rr (pink) from RR (red) and rr (white). 

So, the correct answer is '1:2:1'.

Phenotypic and genotypic ratio is similar in case of ________________.

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Complete dominance

  2. Incomplete dominance

  3. Over dominance

  4. Epistasis

Show answer
Correct Option: B
Explanation:

Incomplete dominance is the phenomenon of neither of the two alleles being dominant  so that expression in the hybrid is intermediate between the expressions of the two alleles in homozygous state. $F _2$ phenotypic ratio is : 2 : 1, similar to genotypic ratio.

Please select the structural character of community.

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. Dominance

  2. Physiognomy

  3. Decomposition

  4. $1$ and $2$ both

Show answer
Correct Option: A
Explanation:
A new community flourishes on the remaining of an old community which have been degraded at very minute organic substances by decomposers with a process of decomposition. The new community shows dominance over the newly acquired substrate as their structural character to form its colony.

So,  the correct option is 'Dominance'.