Gibberellins (GAs) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence. GAs are one of the longest-known classes of plant hormone. It is thought that the selective breeding (albeit unconscious) of crop strains that were deficient in GA synthesis was one of the key drivers of the "green revolution" in the 1960s, a revolution that is credited to have saved over a billion lives worldwide.

Characteristics of Phylum Chordata

1. (Noton; back and chorda; cord).
2. Kingdom: Animalia
3. Presence of a notochord
4. They are backboned animals (vertebrates),
5. Most of the living chordates are familiar vertebrate animals.
6. Presence of dorsal hollow nerve cord
7. Blood vascular system: Present, closed type
8. Ventral heart, hepatic portal system and RBC are present.
9. Germ layer: Triploblastic.
10. Symmetry: bilateral symmetry body.
11. Coelom: Present. Well developed
12. Presence of gill (pharyngeal) slits
13. Presence of post **** tail

Phylum Chordata is divided into four sub-phylum:

1. Hemichordata,
2. Urochordata,
3. Cephalochordata
4. vertebrata or Craniata

Factors affecting enzyme activity

Enzyme activity can be affected by a variety of factors, such as temperature, pH, and concentration.

Enzymes work best within specific temperature and pH ranges, and sub-optimal conditions can cause an enzyme to lose its ability to bind to a substrate.

• Temperature: Raising temperature generally speeds up a reaction, and lowering temperature slows down a reaction. However, extreme high temperatures can cause an enzyme to lose its shape (denature) and stop working.

• pH: Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity. Extreme pH values can cause enzymes to denature.

• Enzyme concentration: Increasing enzyme concentration will speed up the reaction, as long as there is substrate available to bind to. Once all of the substrate is bound, the reaction will no longer speed up, since there will be nothing for additional enzymes to bind to.

• Substrate concentration: Increasing substrate concentration also increases the rate of reaction to a certain point. Once all of the enzymes have bound, any substrate increase will have no effect on the rate of reaction, as the available enzymes will be saturated and working at their maximum rate.

Glycosidic Bond: Certain type of functional group which joins a sugar molecule to another group is called glycosidic bond. Another group may or may not be another carbohydrate.

Peptide Bond: A chemical bond formed between two molecules; when the carboxyl group of one molecule reacts with the amine group of another molecule; is called peptide bond (amide bond). A molecule of water is released during this reaction. This is a dehydration synthesis reaction and usually occurs between two amino acids. This is also known as a condensation reaction. The resulting CO – NH bond is called a peptide bond. The resulting molecule is called an amide. The four atom functional group – C (=O)NH – is called an amide group or a peptide group.

Phospho-diester Bond: A group of strong covalent bonds between a phosphate group and two other molecules over two ester bonds is called a phosphor-diester bond. Phosphodiester bonds make the backbone of the strands of DNA and hence are central to all life on Earth. In DNA and RNA, the phosphodiester bond is the linkage between the 3’ carbon atom of one sugar molecule and the 5’ carbon atom of another.

Nucleic acids

• Nucleic acids are long chain polymers of nucleotides; hence called Polynucleotides
• They are found inside nucleus, hence called Nucleic acids
• 2 types of nucleic acids:
• DNA
  • Deoxyribonucleic Acid
  • Specify order of amino acids in a polypeptide
  • Store genetic information, has capacity to duplicate
  • Double-stranded structure                                                           
• RNA
  • Ribonucleic acid
  • Helps in Polypeptide synthesis
  • Convey genetic information, cannot self replicate
  • Single stranded structure

Polysaccharides

• Polysaccharides contain a large number of monosaccharide units joined together by glycosidic linkages.
• These are the most commonly encountered carbohydrates in nature.
• They mainly act as the food storage or structural materials.
• Some examples of polysaccharides are:
  • Starch
  • Cellulose
  • Glycogen

Proteins are complex biomolecules that are made up of smaller units known as amino acids. 

Due to different rearrangement of amino acids, the structure of proteins divides into four types:

• Primary- the covalent linkages of the proteins
• Secondary- the linear peptide chains fold either into an alpha-helical structure(coiled) or a beta-pleated structure(sheets) which contain hydrogen bonds.

• Tertiary- The arrangement and interconnection of proteins into specific loops and bends forms the tertiary structures. This structure contains hydrogen, ionic and disulfide bonds.
• Quarternary- this structure is proteins containing more than one peptide chain.

Primary Metabolites

These are the chemical compounds produced during the growth and development, processes. They are also involved in the primary metabolic processes of respiration and photosynthesis. The primary metabolites are formed in the growth phase. They maintain the physiological functions of the body and are known as central metabolites. They are the intermediate products of anabolic metabolism, which are used by the cells for the formation of essential macromolecules.

Secondary Metabolites

These compounds are produced by the organisms that are not required for primary metabolic processes. However, they can be important ecologically or otherwise. Secondary metabolites are considered to be the end products of primary metabolites because they are derived by the pathways in which the primary metabolites involve.

For eg., antibiotics, toxins, pheromones, enzyme inhibitors, etc. Streptomycetes and related actinomycetes are the sources of novel secondary metabolites.

• A nucleotide is an organic molecule with a basic composition of a nitrogenous base, pentose sugar and phosphate.
• DNA and RNA are polynucleotides, which contain a chain of nucleotides monomers with different nitrogenous bases.
• Nucleotides are essential for carrying out metabolic and physiological activities.
• ATP (Adenosine triphosphate) acts as the energy currency of cells. Nucleotides form various coenzymes and cofactors, such as NAD, NADP, FAD, coenzyme A, etc. and are essential for many metabolic processes.

Lipids

• Lipids are Heterogeneous organic compounds. They contain Carbon, hydrogen, less amount of oxygen, phosphorus, nitrogen, sulphur
• These are Water insoluble; therefore they form part of membranes that divide water components in the body
• Lipids perform the following functions:
  • Energy storage in the form of Oils & fats
  • Structural roles in Cell membrane
  • Messenger (steroid hormones)
  • Constituents of Plants pigments chlorophyll, carotene etc, Wax, rubber, Vitamins A, E, K
  • Fat acts as an insulator that conserves body heat in animals
  • Fat underneath the skin also act as shock absorber

Amino acids are normal components of cell proteins (called amino acid). They are 20 in number specified in genetic code and universal in viruses, prokaryotes and eukaryotes. Otherwise amino acids may be termed rare amino acids, which take part in protein synthesis e.g. hydroxyproline and non- protein amino acids do not take part in protein synthesis e.g. Ornithin, citrullin, gama-aminobutyric acid (GABA) a neurotransmitter, etc.

Chemical Composition Tests Available:

1. Chromatography. Gas Chromatography. Ion Chromatography. Liquid Chromatography.
2. Mass Spectroscopy. GC Mass Spectroscopy (GC-MS) Inductively Coupled Plasma (ICP-MS)
3. Spectroscopy. FTIR (Solution & Pellet) X-Ray - EDS & XRF Analysis. Inductively Coupled Plasma (ICP-AES)

One has to perform a chemical analysis in order to find the type of organic compounds are found in living organisms. We can take any living tissue (a vegetable or a piece of liver, etc.) and grind it in trichloroacetic acid (Cl3CCOOH) using a mortar and a pestle. We obtain a thick slurry.

A person lying in comma neither responds to environmental stimuli nor has self-consciousness. He/she is supported by machines to carry out the vital life processes and he/she is brain-dead. Some of these patients never come back to normal life. Such persons can neither be considered as living nor non-living.

A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. A pteridophyte is a vascular plant that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. Ferns, horsetails, and lycophytes are all pteridophytes.

The single-celled prokaryotic microorganisms with various range of characteristics are called Eubacteria or true bacteria. These types of microorganisms are found in almost all conditions. They do not consist of membrane nuclei. The cell wall of Eubacteria is made up of peptidoglycans in a cross-linked chain pattern.

Three importance of classification are: 

1. It helps in the identification of living organisms as well as in understanding the diversity of living organisms. 
2. To understand and study the features, similarities and differences between different living organisms and how they are grouped under different categories. 
3. It is essential to understand the inter-relationships among the different groups of organisms. 

Carl Woese proposed the six- kingdom classification. These six kingdoms are Kingdom Archaebacteria, Kingdom Eubacteria, Kingdom Protista, Kingdom Fungi, Kingdom Plantae, and Kingdom Animalia. Woese found that the six kingdoms naturally cluster into three main categories, based on the sequence of 16s ribosomal RNA genes. He called these categories as domains of life. These domains are Bacteria, Archaea, and Eukarya. He also believed that these domains have originated from common ancestors called Progenote.

- Archaebacteria are the oldest known living organisms. They are single- celled and thrive in extremely hot boiling water found in environments

- Eubacteria are also single- celled bacterial organisms. Eubacteria are very common and well- known to us as parasites but some bacteria are also commensal and used for the production of many antibiotics or food material.

- The Fungi kingdom is recognizable to us like mushrooms, molds, mildews, and yeasts. Fungi are multi- celled organisms. - Protista or Protozoa are single- celled organisms but are more complex than eubacteria. The Protista kingdom includes algae and slime molds.

- The Plantae kingdom includes all flowering plants, mosses, and ferns. Plants are multi- celled, complex organisms and are Autotrophic except for a few.

- The largest kingdom is the Kingdom of Animalia. There is a wide variety of organisms ranging from sponges to blue whales.

Terrestrial adaptation necessitated the production of lesser toxic nitrogenous wastes like urea nd uric acid for conservation of water. Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals. Ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood which is filtered an excreted out by the kidneys. Some amount of urea may be retained in the kidney matrix of some of these animals to maintain a desired osmolarity.

Skeletal muscle is a voluntary muscle, which means that we can actively control its function. It's attached to the bone and forms a distinct organ of muscle tissue, blood vessels, tendons, and nerves that covers our bones and allows movement. 

The functional unit of a skeletal muscle fiber is the sarcomere, a highly organized arrangement of the contractile myofilaments actin (thin filament) and myosin (thick filament), along with other support proteins.

Pyruvic acid is first altered in the transition reaction by removal of a carbon and two oxygens (which form carbon dioxide). When the carbon dioxide is removed, energy is given off, and NAD+ is converted into the higher energy form NADH. Coenzyme A attaches to the remaining 2-C (acetyl) unit, forming acetyl Co-A. Pyruvic acid supplies energy to living cells through the citric acid cycle (also known as the Krebs cycle) when oxygen is present (aerobic respiration); when oxygen is lacking, it ferments to produce lactic acid. Pyruvate is an important chemical compound in biochemistry.

Cellular respiration has three main steps: glycolysis, the citric acid cycle, and oxidative phosphorylation, where oxygen is used. Glycolysis is the first step in cellular respiration, and it occurs in the main compartment of the cell: the cytoplasm. Oxygen is the final electron acceptor at the end of the electron transport chain of aerobic respiration. In the absence of oxygen, only a few ATP are produced from glucose.

The respiratory quotient (or RQ or respiratory coefficient), is a dimensionless number used in calculations of basal metabolic rate (BMR) when estimated from carbon dioxide production. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body. The respiratory quotient (RQ) measures the ratio of the volume of carbon dioxide (Vc) produced by an organism to the volume of oxygen consumed (Vo). This is represented by the following equation: This quotient is useful because the volumes of CO2 and O2 produced depends on which fuel source is being metabolized.