Explanation

 Trial-and-error learning involves repeatedly trying different actions or strategies until one leads to a successful outcome.

Classical conditioning, on the other hand, is a type of learning that involves associating two stimuli, such as a neutral stimulus (like a bell) with a naturally occurring stimulus (like food).

The association leads the animal to respond to the neutral stimulus as if it were the natural stimulus.

This process doesn't require trial and error; the response is learned through repeated pairings of the stimuli. 

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

 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

 The endometrium is the inner lining of the uterus, and this is where a fertilized embryo implants to begin pregnancy.

Explanation

The most important hormone in initiating and maintaining lactation after birth is prolactin. 

Prolactin is the hormone responsible for stimulating milk production in the breasts. 

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

 The pattern of sex determination found in Drosophila is b. XY–XX. 

In Drosophila, females have two X chromosomes (XX) 

While males have one X chromosome and one Y chromosome (XY). 

Explanation

In butterflies, the female is XY or X0. 

Butterflies have a unique sex determination system where males have two or more X chromosomes (XX, XXX, etc.)

And females have one X chromosome and either another X or no second sex chromosome (XY or X0).

This differs from humans and most mammals, where females are XX and males are XY. 

Explanation

A permanent change in the genetic structure of a gene is called a mutation. 

A mutation refers to a change in the DNA sequence of a gene, which can lead to alterations in the protein it encodes. 

Explanation

 A chromosome with unequal length of its arms is Submetacentric. 

A submetacentric chromosome has a centromere slightly off-center, resulting in two unequal arms.