Question

Holandric genes/direct transmission of traits from father to son occurs through.
A. Autosomes
B. X-chromosome
C. Y-chromosome
D. None of the above

Answer 1

Hint: Mendel told that something was being stably passed down, unchanged. from parent to offspring through the gametes, over successive generations. He called these things as 'factors' We now call these factors as "genes". Therefore, a gene is defined as the functional unit of inheritance. The gene contains information that is required to express a particular trait in an organism.

Complete answer: Holandric traits are the traits that are passed from male to male only that is from father to son. There are two sex hormones present in human male X and Y. But the X chromosome is common to both male and female. Now let us match this with given options:
Autosomes:- They are the pair of chromosomes that are not involved in the determination of sex . There are 22 pairs of autosomes present in a human.
X- chromosome :- X-chromosome does not pass directly from one parent to the offspring of the same sex but follows a criss-cross inheritance, i.e., it is transferred from one sex to the offspring of the opposite sex. In other words, in criss-cross inheritance a male transmits his traits to his grandson through his daughter (Diagynic), while a female transmits the traits to her granddaughter through her son (Diandric). So they are called criss cross inheritance.
Y-chromosome: These are Y-linked by traits that inherit from male to male only. Examples include:- (i) Porcupine skin (ii) TDF (Testis determining factor). These are called holandric traits.
None of the above: this option cannot be correct as option c is correct.

Our required answer is C) Y-chromosome.

Note: There are present sex limited and sex influence traits also:-
> Sex limited traits :- The genes of sex limited traits are autosomal and they are found in both sexes but express in one sex only. Examples: (i) Milk glands in female (ii) Beard in man
> Sex influenced traits :- These are the autosomal genes that are influenced by the sex of the bearer. These traits appear more frequently in one sex than in the other.
(i) Pattern baldness (affected by male sex hormone/testo- sterone)