The glands of the system secrete chemical substances that are collectively known as . these chemicals diffuse into the bloodstream and communicate with distant cells called cells.

The correct answer will be option-

1. Endocrine glands

2. Hormones

3. Target cells

Explanation:

Animal cells communicate with each other through one of the signalling ways: autocrine, Paracrine and endocrine signalling.

Endocrine signalling occurs when a chemical is secreted by a cell acts on a target cell which is distant from the producer cell.

The group of cells called tissues (glands) which secretes the chemical is thus known as an endocrine gland and the chemical secreted by the endocrine gland is known as the hormone.  

A hormone acts on the distant cell after it gets diffused in the bloodstream and gets transported to the target cell.

spiders belong to a group of arachnids.

arachnids have the following traits :

they have two body parts.

they have eight legs unlike insects which have 6 legs.

they have no wings.

these traits distinguish them from insects.

the information that antonio is doubting us the statement that spiders differences are as a result of being first to evolve.

this is because the evolution of one species is independent of the other species.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.