Question Video: Recalling the Key Component of Plant Cell Walls | Nagwa Question Video: Recalling the Key Component of Plant Cell Walls | Nagwa

Question Video: Recalling the Key Component of Plant Cell Walls Biology

The picture shows the cells of an organism belonging to the kingdom Plantae under a microscope. The walls surrounding the cells are visible. What is the main component of these walls?

02:50

Video Transcript

The picture shows the cells of an organism belonging to the kingdom Plantae under a microscope. The walls surrounding the cells are visible. What is the main component of these walls? (A) Glucose, (B) chitin, (C) cellulose, or (D) peptidoglycan.

This question is asking us about the structure of plant cell walls. So let’s start by reviewing some of the facts about the kingdom Plantae. The kingdom Plantae is one of the five kingdoms that organisms can be classified into. Nearly 400000 different species of plants have been identified. But they are unified by having certain characteristics in common. Organisms in the kingdom Plantae are eukaryotes, which means their cells contain a membrane-bound nucleus and other membrane-bound organelles. They also have a cell wall around the cells, which is utilized for structure and support.

So what are these cell walls made of if they can perform these functions? Let’s have a look. The Plantae kingdom is not the only kingdom that utilizes cell walls. Fungi, most species of Monera, and some protists also have these structures. However, they are made of different materials. Fungi and fungi-like protists have cell walls made of a very strong polysaccharide called chitin, the same substance that is found in the exoskeleton of insects. Monera have cell walls made of peptidoglycan, a substance made of sugars and amino acids. The cell walls of plants and the plant-like protists are made up of a strong polysaccharide called cellulose.

Poly- means many. So cellulose is made up of many single sugar molecules, linked together to form fibers. These fibers then bind together to form a tough cell wall. This provides structure and support.

Let’s therefore return to our question which is asking what is the main component of plant cell walls. We now know that chitin is found in the cell walls of fungi and peptidoglycan is found in the cell walls of Monera. So answers (B) and (D) are incorrect.

Next, let’s discuss option (A). Glucose is a monosaccharide, which is made during the process of photosynthesis. It is then used by plants for respiration or to make other substances, such as fructose, the sugar found in fruits; sucrose; and cellulose, to name just a few. As it is a simple, soluble sugar, it cannot be used for structural purposes, so we can eliminate this option.

We now know that the correct answer is (C). The main component of cell walls of organisms belonging to the kingdom Plantae is cellulose.

Join Nagwa Classes

Attend live sessions on Nagwa Classes to boost your learning with guidance and advice from an expert teacher!

  • Interactive Sessions
  • Chat & Messaging
  • Realistic Exam Questions

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy