All questions of Water and Its Solutions for Grade 9 Exam

The first major break from the Linnean model came from Thomas Whittaker. In 1969 Whittaker proposed a "five kingdom" system in which three kingdoms were added to the animals and plants: Monera (bacteria), Protista, and Fungi.

Explanation:

Archaebacteria are microorganisms that belong to the domain Archaea. They are prokaryotic organisms, meaning they lack a true nucleus and other membrane-bound organelles that are common in eukaryotic cells. Archaebacteria are known to survive in extreme environmental conditions that would be lethal for most other organisms. This is due to several factors, but the most important one is their rigid cell wall.

Rigid Cell Wall:

Archaebacteria have a unique cell wall composition that is different from that found in other bacteria. Their cell walls are made up of a complex polysaccharide called pseudomurein, which is more resistant to heat, acids, and other harsh environmental conditions than the peptidoglycan found in other bacterial cell walls. This rigid cell wall provides the archaebacteria with a protective barrier that helps them to withstand extreme temperatures, pH levels, and pressures.

Other Factors:

Apart from the rigid cell wall, there are several other factors that contribute to the ability of archaebacteria to survive in extreme environments. These include:

1. Unique metabolic pathways: Archaebacteria have evolved unique metabolic pathways that allow them to extract energy and nutrients from the environment in which they live. These pathways allow them to survive in environments that would be toxic to other organisms.

2. Resistance to radiation: Some archaebacteria are known to be resistant to high levels of radiation, which allows them to survive in environments such as hot springs and deep-sea hydrothermal vents.

3. Adaptability: Archaebacteria are highly adaptable and can adjust their metabolism and other cellular processes in response to changes in their environment. This allows them to survive and thrive in a wide range of conditions.

Conclusion:

In conclusion, archaebacteria can survive in extreme conditions because of their unique cell wall composition, as well as other factors such as their metabolic pathways, radiation resistance, and adaptability. Their ability to survive in extreme environments makes them important models for studying the origin and evolution of life on Earth.

• Mushrooms are the commonly known form of Basidiomycetes, called bracket fungi or puffballs.
• They grow in soil, on logs and tree stumps and in living plant bodies as parasites, e.g., rusts and smuts.

Asexual Reproduction in Fungi by Conidiophores:

Asexual reproduction is a type of reproduction in which offspring arise from a single organism, and inherit the genes of that parent only. Fungi reproduce both sexually and asexually. Asexual reproduction in fungi takes place through conidiophores.

Conidiophores:

Conidiophores are specialized structures that produce conidia or conidiospores. These are asexually produced spores that develop on the surface of the conidiophore. Conidiophores are produced by many different types of fungi, including both molds and yeasts.

How Conidiophores work:

Conidiophores are produced by the mycelium of the fungus. They are typically found in clusters, and can grow to be several millimeters in length. The conidiophore is composed of several cells, including a basal cell, a stalk cell, and a terminal cell. The terminal cell is where the conidia are produced.

The conidia are formed by a process called conidiation. This process involves the development of a small bud on the surface of the terminal cell. As the bud grows, it becomes surrounded by a protective layer of cells, which eventually break apart to release the conidiospore.

Advantages of Asexual Reproduction:

Asexual reproduction has several advantages for fungi. First, it allows for rapid reproduction, since no mating is required. This is particularly important in environments where conditions are favorable for growth, but may not be stable over a long period of time.

Second, asexual reproduction allows for the production of large numbers of offspring that are genetically identical to the parent. This can be advantageous in environments where the parent organism is well adapted to the local conditions, since the offspring will also be well adapted.

Third, asexual reproduction allows for the spread of fungi over long distances, since the conidia can be carried by wind or other means.

Conclusion:

In conclusion, the asexual reproduction in fungi takes place by conidiophores. These specialized structures produce conidia or conidiospores, which are asexually produced spores that develop on the surface of the conidiophore. This type of reproduction has several advantages for fungi, including rapid reproduction, large numbers of offspring, and the ability to spread over long distances.

Thermoacidophiles are the bacteria that survives in hot springs because of branched chain lipids in the cell membranes
the primitive prokaryotes responsible for the production of biogas from the dung of ruminant animals include the methanogens
halophiles are the bacteria that can live in the saline habitats

Arranging organisms on the basis of their shared similar or derived characters that differ from ancestral characters, will produce a phylogenetic tree called cladogram. Depending upon the type of system of classification, organisms are classified into two kingdoms or three kingdoms, four kingdoms, five kingdoms and now into six kingdoms.

Unicellular vs Multicellular

Unicellular organisms are those that are composed of a single cell, while multicellular organisms are those that are made up of multiple cells.

Algae

Algae are a diverse group of aquatic organisms that can be found in a variety of environments, from freshwater to saltwater. They can be either unicellular or multicellular, depending on the species.

Plantae

Plants, which belong to the kingdom Plantae, are multicellular organisms that are capable of photosynthesis. They are made up of a variety of specialized cells that work together to carry out the functions necessary for growth and survival.

Protozoa

Protozoa are a group of unicellular eukaryotic organisms that are found in a variety of environments, including water, soil, and the digestive tracts of animals. They are capable of a wide range of metabolic activities, including photosynthesis, and are an important part of many ecosystems.

Animalia

Animals, which belong to the kingdom Animalia, are multicellular organisms that are capable of movement and are characterized by a wide range of specialized tissues and organs. They are found in a variety of environments, from the depths of the ocean to the highest mountains.

Why is the answer A?

The answer to this question is A because algae can be either unicellular or multicellular. Some species of algae, such as Chlamydomonas, are unicellular, while others, such as kelp, are multicellular. Therefore, it is not possible to make a clear distinction between unicellular and multicellular when it comes to algae.

Cyanobacteria and Heterocysts

Cyanobacteria, also known as blue-green algae, are a group of prokaryotic organisms that are found in various aquatic and terrestrial environments. They are photosynthetic and use sunlight to produce energy and organic compounds.

Heterocysts are specialized cells that some cyanobacteria have. They are able to fix atmospheric nitrogen into a form that can be used by the cell. Heterocysts are important for cyanobacteria because, unlike other organisms, they cannot take up nitrogen from the soil. Therefore, they need to be able to produce their own nitrogen.

The incorrect statement about cyanobacteria is option B, which states that they lack heterocysts. In fact, some cyanobacteria do have heterocysts, which are specialized cells that are able to fix atmospheric nitrogen. However, not all cyanobacteria have heterocysts.

Therefore, the correct statement about cyanobacteria is:
- They are photoautotrophs, meaning they use sunlight to produce energy and organic compounds.
- They often form blooms in polluted water bodies, which can be harmful to other organisms in the ecosystem.
- They have chlorophyll A similar to green plants, which allows them to capture sunlight for photosynthesis.
- Some cyanobacteria have heterocysts, specialized cells that are able to fix atmospheric nitrogen.

Extreme Saline Conditions and Organisms

Extreme saline conditions refer to environments that have high levels of salt concentration, such as salt pans, salt lakes, and salt marshes. These environments pose significant challenges for most organisms due to the osmotic stress caused by the high salt concentration. However, some organisms have adapted to these extreme conditions and can thrive in saline habitats. One group of organisms that is well-suited to extreme saline conditions is the Archaebacteria.

Archaebacteria and Extreme Saline Conditions

Archaebacteria, also known as Archaea, are a group of single-celled microorganisms that are distinct from both eubacteria and eukaryotes. They are known for their ability to inhabit extreme environments, including high-temperature areas, acidic environments, and saline habitats. Archaebacteria that can be found in extreme saline conditions belong to the halophile category.

Adaptations of Halophilic Archaebacteria

Halophilic Archaebacteria have several adaptations that allow them to survive in extreme saline conditions:

1. Compatible Solutes: Halophiles produce or accumulate compatible solutes, such as potassium ions, amino acids, and polyols, to balance the osmotic pressure and prevent water loss. These compatible solutes help maintain the cell's internal water content and protect essential cellular structures.

2. Pigments: Some halophiles produce pigments, such as bacteriorhodopsin, which are involved in energy generation through photosynthesis or light-driven ion pumps. These pigments enable halophiles to utilize light as an additional energy source in saline environments.

3. Cell Membrane Adaptations: The cell membranes of halophiles have unique lipid compositions that help maintain membrane integrity and function in high salt concentrations. These adaptations include increased levels of branched-chain fatty acids and ether-linked lipids.

4. Enzyme Adaptations: Halophilic enzymes have adapted to function in high salt concentrations by having a higher number of acidic amino acids on their surfaces. This allows the enzymes to maintain their structural stability and activity in saline environments.

Conclusion

In conclusion, among the organisms listed, only the Archaebacteria (option B) can be found in extreme saline conditions. Archaebacteria, specifically the halophilic group, have evolved various adaptations to survive in high salt environments, including the production of compatible solutes, unique cell membrane compositions, and specialized enzymes. These adaptations allow halophiles to maintain cellular homeostasis, protect essential cellular structures, and utilize light as an additional energy source.

**Explanation:**

In the five-kingdom classification system, organisms are classified into five main kingdoms based on their cellular structure, mode of nutrition, and complexity of their body organization. The five kingdoms are:

1. **Monera:** This kingdom includes prokaryotic organisms, which are single-celled and lack a true nucleus. They are further divided into bacteria and blue-green algae (cyanobacteria).

2. **Protista:** This kingdom consists of eukaryotic organisms that are mostly unicellular. They have a true nucleus and are more complex than organisms in the Monera kingdom. Protists are a diverse group that includes various types of microorganisms, such as algae, protozoa, and slime molds.

3. **Fungi:** This kingdom includes eukaryotic organisms that are heterotrophic and have a cell wall made of chitin. Fungi obtain nutrients by absorbing them from their surroundings. They include mushrooms, yeasts, molds, and mildews.

4. **Plantae:** This kingdom consists of multicellular eukaryotic organisms that are photosynthetic. They possess chloroplasts and cell walls made of cellulose. Plants are autotrophic and provide oxygen, food, and shelter to other organisms. They include trees, shrubs, herbs, and mosses.

5. **Animalia:** This kingdom includes multicellular eukaryotic organisms that are heterotrophic and lack cell walls. They have specialized tissues and organs, and most animals can move from place to place. Animals obtain their food by ingestion.

**Chlamydomonas** and **Chlorella** are both unicellular green algae. They are photosynthetic organisms that possess chloroplasts and cell walls made of cellulose. These characteristics are similar to organisms in the Plantae kingdom. However, unlike plants, they lack true roots, stems, and leaves. Therefore, they do not fit into the Plantae kingdom.

Instead, Chlamydomonas and Chlorella are classified under the Protista kingdom. Protists are a diverse group that includes various types of microorganisms, including algae. Chlamydomonas and Chlorella are examples of unicellular algae that are classified as protists. They are not considered plants because they lack the complex body organization and tissue differentiation found in true plants.

Therefore, the correct answer is option 'D' - Protista.

Explanation:

Cyanobacteria are a group of autotrophic organisms classified under Kingdom Monera
Cyanobacteria, also known as blue-green algae, are a group of photosynthetic bacteria that can produce their own food through photosynthesis. They are classified under the Kingdom Monera, which consists of prokaryotic organisms that lack a true nucleus.

Characteristics of Cyanobacteria:
- Cyanobacteria have chlorophyll and other pigments that allow them to carry out photosynthesis.
- They can be found in a wide range of environments, from freshwater to marine habitats.
- Some cyanobacteria are capable of nitrogen fixation, converting atmospheric nitrogen into a form that plants can use.
- Cyanobacteria can form colonies or filaments, and some species can even produce toxins under certain conditions.

Importance of Cyanobacteria:
- Cyanobacteria play a crucial role in the environment as primary producers, providing food and oxygen for other organisms.
- Some cyanobacteria are used in biotechnology and research due to their ability to fix nitrogen and produce bioactive compounds.
- However, some cyanobacteria can also cause harmful algal blooms in bodies of water, posing risks to aquatic life and human health.
In conclusion, cyanobacteria are autotrophic organisms classified under Kingdom Monera, and they play important roles in various ecosystems.

Understanding the Concept
The question relates to the reproductive mechanisms in fungi, particularly focusing on how sexual reproduction occurs in certain fungal species.
Key Points of the Answer
- Sex Organs:
In many fungi, sex organs are absent, which sets them apart from higher organisms that have distinct male and female reproductive structures.
- Plasmogamy:
This term refers to the fusion of two vegetative or somatic cells, which is a critical step in the sexual reproduction of fungi. During this process, the cytoplasm of two parent cells merges, but their nuclei remain distinct initially.
- Different Strains or Genotypes:
The fusion occurs between cells from different strains or genotypes, which is essential for increasing genetic diversity in the resulting offspring.
- Dikaryotic Structure:
After plasmogamy, the resulting cell possesses two nuclei (one from each parent) and is termed dikaryotic. This stage is a unique characteristic of fungal sexual reproduction.
- Formation of Basidium:
Eventually, the dikaryotic structure gives rise to a basidium, which is a specialized reproductive structure found in certain fungi, notably in the class Basidiomycetes. The basidium is where karyogamy (the fusion of nuclei) occurs, leading to the production of spores.
Conclusion
Thus, the correct answer is option 'B': "Absent, plasmogamy, different, basidium." This highlights the unique reproductive strategies that fungi employ, distinguishing them from more familiar reproductive processes seen in higher organisms.