Teh cell wall remains present only in plant celsl. It is totally absent in animals.

A holoblastic cleavage producing blastomeres of equal size

Yes, the  threatened species are those which are suffering from the danger of extinction. An endangered species is a population of organisms which is at risk of becoming  extinct because it is either less in number or threatened by changing environmental or predation parameters, e.g. blue whale, tiger, bonobo, gaint panda etc.

The pituitary is often called the master gland because the hormones it secretes play an active part in controlling the activities of all the other endocrine glands. This impressive power is wielded from two little bumps at the base of the brain, about midway between the ears at eye level.

insects   The Malpighian tubule system is a type of excretory and osmoregulatory system found in some Uniramia (Insects and Myriapoda),

Butterflies belong to the order Lepidoptera.

During anaphase I, homologous chromosomes are pulled from each other and move to opposite poles.

Anopheles mosquito is the vector of malaria.

A goitre is a swelling of the neck or larynx resulting from enlargement of the thyroid gland (thyromegaly), associated with a thyroid gland that is not functioning properly. The main reason is deficiency of iodine in the diet which is required for the synthesis of thyroid hormones.

 Malaria, filaria and yellow fever are caused by mosquitoes.