Question

The four elements called "big-four \(^{n}\) which make up 95 of all elements found in a living system are (a) \(\mathrm{C}, \mathrm{H}, \mathrm{O}, \mathrm{N}\) (b) \(C, H, O, P\) (c) \(C, H, 0, S\) (d) \(C, N, O, P\)

Short answer

The 'big-four' elements that make up 95% of all elements found in a living system are (a) \(\mathrm{C}, \mathrm{H}, \mathrm{O}, \mathrm{N}\).

Step-by-step solution

Identify the Most Abundant Elements in Living Systems

To answer this question, recall or research the most abundant elements that are known to be crucial for life. These elements are commonly found in organic molecules such as carbohydrates, proteins, lipids, and nucleic acids.

Match the elements to the options provided

The 'big-four' elements that satisfy the requirement of being most abundant in living systems are Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N). Eliminate the options that don't contain all four of these elements.

Select the Correct Option

Comparing the elements with the options provided, option (a) \(\mathrm{C}, \mathrm{H}, \mathrm{O}, \mathrm{N}\) is the only one that lists all four elements correctly. Therefore, it is the correct answer.

Key concepts

Big-Four Elements

In biology, the term 'big-four elements' refers to carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), which are the most abundant and essential elements in living organisms. These elements are the building blocks of organic molecules and are fundamental to the structure and function of biological systems.

Carbon is the central element in organic chemistry because of its ability to form four covalent bonds, leading to a diverse range of compounds. Hydrogen bonds with carbon to create hydrocarbons, which are the foundation of many complex organic molecules. Oxygen is crucial for respiration, a process that provides energy to living cells, and is also a part of water molecules, which are vital for life. Nitrogen is a key component of amino acids, the building blocks of proteins, and nucleic acids like DNA and RNA, which store and transmit genetic information.

Understanding the role of the 'big-four' enables students to grasp the chemical basis of life and explains why these elements are so prevalent in living organisms.

Organic Molecules

Organic molecules are compounds primarily composed of carbon atoms bonded to hydrogen, oxygen, nitrogen, and other elements. These molecules form the basis of organic chemistry and are categorized into four main types: carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

Carbohydrates are sugars and starches that serve as energy sources and structural components in cells.

Lipids

Lipids, including fats and oils, are essential for energy storage and maintaining cell membranes.

Proteins

Proteins are made from amino acids and are necessary for structural support, enzymes, and cell signaling.

Nucleic Acids

Nucleic acids, such as DNA and RNA, carry genetic information and play a critical role in protein synthesis.

The diversity and complexity of organic molecules arise from the various ways carbon atoms can bond to others, creating a vast array of structures and functions essential for life.

Biological Macromolecules

Biological macromolecules are large molecules necessary for life that are built from smaller organic molecules. These macromolecules include carbohydrates, lipids, proteins, and nucleic acids – all of which are polymers made from repeating units called monomers.

Carbohydrate Polymers

For carbohydrates, the monomers are simple sugars like glucose, which form polysaccharides such as starch and cellulose.

Lipid Structures

Lipids are generally not polymers but can form complex structures like cellular membranes through the arrangement of fatty acid molecules.

Protein Chains

Proteins are polymers of amino acids, forming peptide chains that fold into functional three-dimensional shapes.

Nucleic Acid Strands

Nucleic acids are polymers of nucleotides, forming long chains that constitute DNA and RNA.

The synthesis and breakdown of these macromolecules are essential to life processes, including growth, repair, and reproduction. Through the study of biological macromolecules, students can learn how organisms are built and how they function at a molecular level.