Question

ln which of the following pairs, the two items mean one and the same thing?
A. Malleus-Anvil
B. SA node-Pacemaker
C. Leukocytes-Lymphocytes
D. Hemophilia-Lung Cancer

Answer 1

Hint: SA node is located in the right atrium at the junction of the superior vena cava and the auricle of the right. The main job of sinoatrial node cells is to activate the action potential of the heart, which can bypass the heart muscle cells and cause contraction. It produces a normal adult heart rate with a frequency of $70$ to $80$ per minute.

Complete answer:
In the human skeletal system middle ear in the skull part have three ossicles which help in amplification of sound .These ear ossicles are ear ossicles the malleus which is hammer shaped, the incus which is anvil shape and the stapes which is stirrup shaped. So option(A) is incorrect because malleus is hammer shaped.
In a healthy heart, the SA node continuously generates action potentials that regulate the heart rate and is therefore called a natural pacemaker. Hence the correct option is (B).
Lymphocyte is a type of leukocyte, so this option is not correct.
Haemophilia- This is known as a bleeding disease. It is a sex-specific disease that was first studied by John Cotto in $1803$ . bleeding for hours , even with a slight cut. As a result of prolonged bleeding, patients can die from blood loss. Although there is no permanent cure for this disease, normal blood transfusions help check for bleeding by providing the factors necessary for blood clotting. Antihemophilic globulin is available for haemophilia patients.

Hence, the correct answer is option (D).

Note: Haemophilia is a sex linked recessive disorder. The damaged allele produces non-functional proteins which then form a cascade of non-functional proteins involved in blood clotting
The chances of a woman becoming haemophilic are very rare, because the mother of the woman must at least be the carrier and the father must be haemophilic. For example, women only suffer from the disease in a homozygous state( XCXC).Queen Victoria is a carrier of haemophilia and produces individuals with haemophilia. The haemophilia gene is on the X chromosome.
The number of ear ossicles is six three in each ear.