Chapter 28, Problem 1IQ

The plastids of chlorarachniophytes are surrounded by four membranes and enclose a vestigial nucleus called a nucleomorph. What do these facts suggest?

Summary Introduction

To explain: The facts that suggest the plastids of chlorarachniophytes are surrounded by four membranes and enclose a nucleomorph.

Introduction: Protists are microscopic organisms that belong to the kingdom “Protista”. These have been classified into various categories depending upon their mode of nutrition.

Explanation of Solution

The four membranes of chlorarachniophytes indicate the secondary symbiosis of a green alga. Green alga has chloroplasts that originated from the primary endosymbiont. Out of the four membranes of chlorarachniophytes, inner two membranes belong to the chloroplast of green algae. The third membrane belongs from the outer membrane of alga, and the outer membrane belongs from the heterotrophic eukaryotic food vacuole. The vestigial nucleus in the secondary symbiosis of a green alga specifies the process that occurred recently and the genetic sequence of the process toward the origin of green algae.