Explanation

If A · B = 0, it means the vectors A and B are perpendicular.

The magnitude of the cross product is:

|A × B| = |A||B|sinθ

For perpendicular vectors, θ = 90°, so sin(90°) = 1

⇒ |A × B| = AB × 1 = AB

Explanation

The structure formed from ectodermal tissue is Brain. 

The ectoderm is the outermost germ layer in an embryo and develops into the nervous system (including the brain and spinal cord) and the skin. 

Explanation

 In a vertebrate, a reflex action is induced by a sensory nerve. 

A sensory nerve detects the stimulus, which triggers the signal to the spinal cord, leading to the motor neuron response in a reflex action. 

Explanation

The hormone that stimulates the mammary glands to enlarge at puberty is estrogen. 

During puberty, rising levels of estrogen in girls trigger the development of breast tissue by promoting the growth of the ductal system and the accumulation of fat tissue. 

Explanation

The kidneys are responsible for filtering blood and regulating the amount of water and electrolytes excreted in urine.

They can adjust the concentration of urine depending on the body's hydration needs.

This makes them the primary organ for controlling water balance. 

Explanation

 Gonadotropic hormones, like follicle-stimulating hormone (FSH) and luteinizing hormone (LH),

They are specifically secreted by specialized cells called gonadotrophs within the anterior pituitary gland. 

Explanation

According to Einstein, increasing the brightness of a beam of light without changing its color will increase the number of photons. 

Einstein's theory of light posits that light consists of discrete particles called photons.

Brightness is related to the number of photons present in a given area over a specific time.

When you increase the brightness of a light beam, you are essentially adding more photons to that beam,

While keeping the energy of each photon the same (which is related to its frequency and color).

Explanation

The first organic compound prepared in the laboratory was Urea. 

German chemist Friedrich Wöhler synthesized urea from ammonium cyanate in 1828,

Marking a significant milestone in organic chemistry. 

Explanation

A body moving in a circular path with constant speed has variable acceleration. 

While the speed remains constant, the direction of the velocity vector is constantly changing as the body moves around the circle.

Since acceleration is the rate of change of velocity, and velocity is changing (even though speed is constant),

The body experiences a constant magnitude of acceleration

But the direction of that acceleration changes at every point on the circle.

This makes the acceleration variable. 

Explanation

Affinity for oxygen refers to how readily an element or compound combines with oxygen.

Magnesium (Mg) is a highly reactive alkaline earth metal that readily loses its two electrons to form a positive Mg2+ ion.

This ion then readily combines with oxygen to form magnesium oxide (MgO), demonstrating a strong affinity for oxygen.