VII. Answer briefly.
Write the four types of bacteria, based on their shape.
The four types of bacteria based on their shape are:
- Bacilli: Rod-shaped bacteria (e.g., Bacillus anthracis)
- Cocci: Spherical or ball-shaped bacteria (e.g., Staphylococcus, Streptococcus)
- Spirilla: Spiral-shaped bacteria (e.g., Helicobacter pylori)
- Vibrio: Comma-shaped bacteria (e.g., Vibrio cholerae)
What are antibiotics?
Antibiotics are substances produced by living organisms (typically bacteria or fungi) that can kill or inhibit the growth of other microorganisms. They are used to treat bacterial infections. For example, penicillin, which is derived from the mold Penicillium.
What are pathogens?
Pathogens are microorganisms that cause disease in their host. These can include bacteria, viruses, fungi, protozoa, and other parasites. For example, the bacterium Mycobacterium tuberculosis causes tuberculosis, and the virus Influenza causes the flu.
How disease causing microorganisms enter into human beings?
Disease-causing microorganisms can enter human beings through various routes, including:
- Inhalation: Breathing in airborne pathogens (e.g., influenza virus).
- Ingestion: Consuming contaminated food or water (e.g., Salmonella bacteria).
- Contact: Direct contact with infected individuals or surfaces (e.g., touching contaminated surfaces and then touching the face).
- Injections or bites: Through bites from infected insects (e.g., malaria from mosquito bites) or through contaminated needles.
- Cuts and wounds: Through breaks in the skin.
Why microorganisms are essential for agriculture?
Microorganisms are essential for agriculture because they play crucial roles in:
- Nitrogen fixation: Certain bacteria (e.g., Rhizobium) fix atmospheric nitrogen into forms that plants can use, enriching soil fertility.
- Decomposition: Microorganisms decompose organic matter, releasing nutrients back into the soil, making them available for plant uptake.
- Biocontrol agents: Some microorganisms help control pests and diseases in crops (e.g., Bacillus thuringiensis used in Bt cotton).
- Composting: Microbes break down organic waste into compost, which improves soil structure and fertility.
- Symbiotic relationships: Microbes form symbiotic relationships with plants, such as mycorrhizal fungi that enhance water and nutrient absorption by plant roots.
VIII. Answer in detail.
Write a short note on bacteria and its structure.
Bacteria are single-celled prokaryotic microorganisms that are found in virtually every environment on Earth, from soil and water to the human body. They are among the oldest living organisms and are classified under the kingdom Monera.
Structure of Bacteria:
Cell Wall: The outermost layer that provides shape and protection. In many bacteria, it is composed of peptidoglycan.
Cell Membrane: Located just inside the cell wall, it regulates the movement of substances in and out of the cell.
Cytoplasm: A jelly-like substance inside the cell membrane that contains water, enzymes, nutrients, wastes, and gases. It also houses cell structures such as ribosomes.
Nucleoid: An irregularly-shaped region within the cell that contains the bacterial DNA. Unlike eukaryotic cells, bacteria do not have a true nucleus enclosed by a membrane.
Plasmid: Extra-chromosomal DNA present in the cytoplasm. Plasmids can carry genes that provide bacteria with genetic advantages, such as antibiotic resistance.
Ribosomes: The sites of protein synthesis. Bacterial ribosomes are smaller than those found in eukaryotic cells.
Flagella: Long, whip-like structures that aid in locomotion.
Pili (Fimbriae): Hair-like appendages that allow bacteria to attach to surfaces and to each other.
Capsule: A gelatinous layer surrounding the cell wall in some bacteria, which helps in protecting the cell from desiccation and in evading the host’s immune system.
How microorganisms are useful in the field of medicine?
Microorganisms play a vital role in the field of medicine in various ways:
Antibiotics: Many antibiotics are derived from microorganisms. For example, penicillin is produced by the mold Penicillium chrysogenum, and streptomycin is produced by the bacterium Streptomyces griseus. Antibiotics are used to treat bacterial infections.
Vaccines: Vaccines are often made from weakened or inactivated microorganisms. They stimulate the immune system to develop immunity against specific pathogens. For example, the BCG vaccine for tuberculosis is derived from a strain of Mycobacterium bovis.
Probiotics: Beneficial bacteria, such as Lactobacillus and Bifidobacterium, are used in probiotics to promote gut health and enhance the immune system.
Production of Insulin: Genetically engineered bacteria are used to produce human insulin. The gene for human insulin is inserted into bacteria, which then produce insulin that can be harvested and used to treat diabetes.
Research and Development: Microorganisms are used in genetic research and biotechnology. They serve as model organisms in studying fundamental biological processes and in the development of new treatments and drugs.
Bioremediation: Some microorganisms are used to clean up contaminated environments, such as oil spills, by breaking down pollutants.
Write a short note on common human diseases caused by microorganisms.
Microorganisms can cause a variety of diseases in humans, which can be broadly classified based on the type of pathogen involved:
Bacterial Diseases:
Tuberculosis: Caused by Mycobacterium tuberculosis, it primarily affects the lungs but can also affect other parts of the body.
Strep Throat: Caused by Streptococcus pyogenes, it results in sore throat, fever, and swollen lymph nodes.
Cholera: Caused by Vibrio cholerae, it leads to severe diarrhea and dehydration.
Viral Diseases:
Influenza (Flu): Caused by influenza viruses, it results in fever, chills, muscle aches, and respiratory symptoms.
HIV/AIDS: Caused by the human immunodeficiency virus (HIV), it leads to the gradual weakening of the immune system.
Chickenpox: Caused by the varicella-zoster virus, it results in itchy skin rashes and blisters.
Fungal Diseases:
Athlete’s Foot: Caused by fungi of the genus Trichophyton, it leads to itching, burning, and cracked skin on the feet.
Candidiasis: Caused by Candida species, it can affect the mouth, throat, and genital areas.
Protozoan Diseases:
Malaria: Caused by Plasmodium species, it is transmitted by the bite of infected Anopheles mosquitoes and results in fever, chills, and anemia.
Amoebiasis: Caused by Entamoeba histolytica, it leads to severe diarrhea and abdominal pain.
Prion Diseases:
Creutzfeldt-Jakob Disease (CJD): A rare degenerative brain disorder caused by prions, leading to rapid neurological decline and death.
