1. Which organisms are the sole members of the Kingdom Monera?
Correct Answer: B
Kingdom Monera includes only prokaryotic organisms, and bacteria are the sole members of this kingdom. Prokaryotes are organisms that lack a true nucleus and membrane-bound organelles. Their genetic material is present in a nucleoid region instead of a well-defined nucleus. Bacteria are usually unicellular and can survive in a wide range of environments such as soil, water, air, hot springs, deep oceans and even inside other organisms. Some bacteria are autotrophic while others are heterotrophic. They reproduce mainly by binary fission. Because of their simple cellular organization and prokaryotic nature, all bacteria are grouped under Kingdom Monera in the five-kingdom classification.
2. Why are bacteria considered the most abundant microorganisms?
Correct Answer: B
Bacteria are considered the most abundant microorganisms because they are found almost everywhere on Earth. They occur in soil, water, air, and even inside the bodies of plants and animals. Bacteria can survive in extreme environments such as hot springs, deep oceans, deserts, and polar regions. Some live freely in nature while others live as parasites or symbionts. Because of their simple structure, rapid reproduction, and ability to adapt to many environmental conditions, bacteria are present in extremely large numbers in almost every habitat on the planet.
3. Bacteria can survive in extreme habitats such as:
Correct Answer: A
Bacteria are extremely adaptable microorganisms and can live in a wide range of environments. Hundreds of bacteria may be present even in a handful of soil. They are also capable of surviving in extreme habitats where very few other organisms can live. These environments include very hot places like hot springs, extremely dry deserts, very cold regions covered with snow, and deep ocean floors where pressure is very high. Because of their simple structure and special metabolic abilities, bacteria can tolerate extreme temperature, pressure, and salinity, making them one of the most widespread forms of life on Earth.
4. Many bacteria live in or on other organisms as:
Correct Answer: B
Many bacteria live in or on other living organisms and obtain nutrients from them. Such bacteria are called parasites. They depend on the host organism for food and survival and sometimes cause diseases. For example, some bacteria infect humans, animals, or plants and may lead to infections. However, not all bacteria are harmful; many live freely in soil, water, or inside the body without causing harm. Parasitic bacteria specifically live on or inside a host and derive nourishment from it.
5. Bacteria are commonly classified into four groups based on their:
Correct Answer: C
Bacteria are commonly classified into four major groups based on their shape. These include cocci (spherical bacteria), bacilli (rod-shaped bacteria), vibrios (comma-shaped bacteria), and spirilla (spiral-shaped bacteria). This classification helps scientists identify bacteria easily and understand their structural differences.
6. Based on shape, bacteria are commonly classified into how many groups?
Correct Answer: C
Bacteria are commonly classified into four groups based on their shape. These are coccus (spherical), bacillus (rod-shaped), vibrio (comma-shaped), and spirillum (spiral-shaped). This simple morphological classification helps scientists identify and study different bacterial types.
7. Coccus (plural: cocci) bacteria are:
Correct Answer: B
Coccus bacteria are spherical or round in shape. They may occur singly, in pairs, chains or clusters. Examples include Streptococcus and Staphylococcus.
8. Bacillus (plural: bacilli) bacteria are:
Correct Answer: A
Bacillus bacteria are rod-shaped. They are one of the most common bacterial shapes and may occur singly or in chains. An example is Bacillus anthracis.
9. Vibrio bacteria are:
Correct Answer: B
Vibrio bacteria are comma-shaped or curved rods. A well-known example is Vibrio cholerae, the bacterium that causes cholera.
10. Spirillum (plural: spirilla) bacteria are:
Correct Answer: C
Spirillum bacteria are spiral or helical in shape. Their spiral structure helps them move easily in liquid environments.
11. Although bacteria have a very simple structure, they are considered complex mainly because of their:
Correct Answer: C
Bacteria have a very simple cellular structure because they are prokaryotic organisms without a true nucleus or membrane-bound organelles. However, they show very complex behaviour in terms of metabolism, reproduction, and adaptability. Bacteria can survive in extreme environments, reproduce rapidly, and show various modes of nutrition such as autotrophic and heterotrophic. They can also interact with other organisms as parasites, symbionts, or decomposers. Because of these diverse activities and survival strategies, bacteria are considered behaviourally complex despite their simple structure.
12. Bacteria show the most extensive diversity mainly in their:
Correct Answer: B
Compared to many other organisms, bacteria show the greatest metabolic diversity. They can obtain energy and nutrients in many different ways. Some bacteria are autotrophic and produce their own food through photosynthesis or chemosynthesis, while others are heterotrophic and depend on organic matter. They may live freely in soil and water, or as parasites and symbionts in other organisms. Because bacteria can use a wide variety of chemical substances for energy and survive in many environments, they exhibit extremely diverse metabolic activities.
13. Bacteria may be:
Correct Answer: C
Bacteria show great metabolic diversity. Some bacteria are autotrophic and can synthesise their own food from inorganic substances using light energy (photosynthesis) or chemical energy (chemosynthesis). Other bacteria are heterotrophic and obtain their food from organic matter, either as parasites, saprophytes, or symbionts. Because bacteria can obtain nutrition in both ways, they may be autotrophic or heterotrophic depending on the species and environmental conditions.
14. Some bacteria that synthesise their own food from inorganic substrates are:
Correct Answer: A
Some bacteria are autotrophic, meaning they can synthesise their own food from inorganic substances such as carbon dioxide and mineral salts. They use energy from sunlight (photosynthetic bacteria) or chemical reactions (chemosynthetic bacteria) to produce organic compounds. Because they can produce their own food, autotrophic bacteria do not depend on other organisms for nutrition. These bacteria play an important role in nature by contributing to nutrient cycles and energy flow in ecosystems.
15. Autotrophic bacteria that synthesise their own food from inorganic substances may be ______ or ______.
Correct Answer: A
Some bacteria are autotrophic and can synthesise their own food from inorganic substances. These autotrophic bacteria may obtain energy either from sunlight or from chemical reactions. Those that use sunlight are called photosynthetic autotrophic bacteria, while those that obtain energy from oxidation of inorganic chemicals are called chemosynthetic autotrophic bacteria.
16. The vast majority of bacteria are ______, i.e., they depend on other organisms or dead organic matter for food.
Correct Answer: B
Most bacteria are heterotrophic, meaning they cannot prepare their own food. Instead, they depend on other organisms or on dead organic matter for their nutrition. Heterotrophic bacteria may live as saprophytes by feeding on dead and decaying organic matter, as parasites by living on or inside living hosts, or as symbionts in mutually beneficial relationships with other organisms. These bacteria play an important role in ecosystems, especially in decomposition and recycling of nutrients in nature.