Chapter 24.1, Problem 5MI

Summary Introduction

To identify:

The given facts about the animals.

Introduction:

A cell is the structural, functional, and biological unit of all living organisms. It is smallest unit for life. A cell can be prokaryotic or eukaryotic. Eukaryotic cells contain membrane bound cell organelles, that help in functioning of cellular machinery by carrying out biochemical reactions.

Explanation of Solution

Choanoflagellates are the earliest true animals from which all other are likely to evolve. They are free-living unicellular and flagellated eukaryotes. They are known to be closest living relatives of all animals.

Features that mark the branching points of evolutionary tree are tissue systems, presence or absence of body cavities, types of symmetry, and types of development.

Different ways in which animals digest their food are chemical digestion and mechanical digestion. Mechanical digestion breaks the food into very small pieces by chewing in mouth and also in the stomach. In the chemical digestion enzymes are used to break the chewed food into small micromolecules. Like, polysaccharides and proteins in food are break down into monosaccharide and amino acids.