Diversity Of Living Organisms - Olympiad Level MCQ, Class 9 Science - Class 9 MCQ

Most common nitrogen fixing cyanobacteria of paddy fields is Aulosira.
Explanation:
- Cyanobacteria are photosynthetic bacteria that play a crucial role in nitrogen fixation, which is the process of converting atmospheric nitrogen into a form that can be utilized by plants.
- Paddy fields are flooded with water, creating an anaerobic environment. In such conditions, cyanobacteria are the primary nitrogen fixers.
- Among the given options, Aulosira is the most common nitrogen-fixing cyanobacteria found in paddy fields.
- Aulosira is a filamentous cyanobacterium that forms long chains of cells. It has specialized cells called heterocysts, which are responsible for nitrogen fixation.
- Nitrogen fixation by Aulosira in paddy fields helps in providing a steady supply of nitrogen to the rice plants, which is essential for their growth and development.
- Other cyanobacteria mentioned in the options, such as Cylindrospermum, Oscillatoria, and Nostoc, may also be present in paddy fields, but Aulosira is considered the most common and important nitrogen-fixing cyanobacteria in this environment.
Therefore, the correct answer is C: Aulosira.

Kingdom Protista includes:
Life cycle showing sporic meiosis:
- Sporic meiosis is a type of life cycle where the organism alternates between a diploid (sporophyte) and a haploid (gametophyte) phase.
- In this type of life cycle, the diploid sporophyte produces haploid spores through meiosis.
- The spores then develop into haploid gametophytes, which produce gametes through mitosis.
- The gametes fuse to form a diploid zygote, which grows into a new sporophyte.
- Examples of protists that exhibit a life cycle showing sporic meiosis include certain algae and mosses.
Life cycle showing zygotic meiosis:
- Zygotic meiosis is a type of life cycle where the organism spends most of its life cycle in the haploid phase.
- The diploid zygote undergoes meiosis immediately after fertilization, resulting in haploid cells.
- These haploid cells develop into mature organisms, which produce gametes through mitosis.
- The gametes fuse to form a diploid zygote, and the cycle continues.
- Examples of protists that exhibit a life cycle showing zygotic meiosis include certain types of algae, such as Chlamydomonas.
Both B and D:
- Protists in the Kingdom Protista can exhibit a life cycle showing both zygotic meiosis and gametic meiosis.
- In this type of life cycle, the organism alternates between a diploid (sporophyte) and a haploid (gametophyte) phase, similar to sporic meiosis.
- However, the main difference is that the haploid phase produces gametes directly through mitosis, rather than spores.
- Examples of protists that exhibit a life cycle showing both zygotic meiosis and gametic meiosis include certain types of algae, such as Ulva.
Life cycle showing gametic meiosis:
- Gametic meiosis is a type of life cycle where the organism spends most of its life cycle in the diploid phase.
- The diploid organism produces haploid gametes through meiosis.
- These gametes fuse to form a diploid zygote, which grows into a new organism.
- Examples of protists that exhibit a life cycle showing gametic meiosis include certain types of algae, such as Fucus.
Therefore, the correct answer is option C, which states that Kingdom Protista includes both life cycles showing zygotic meiosis (option B) and gametic meiosis (option D).

Protista was first observed by John Hogg in 1860. This kingdom was known as Kingdom 'Protoctista' at that time and consist of unicellular plants and animals. In 1866 Ernst Haeckel coined the term 'Protista' for them.

The wall of Rhizopus hypha is composed of chitin.

• Chitin is a complex polysaccharide that is the main component of the fungal cell wall.


• It is a strong and rigid substance, providing structural support and protection to the hyphae.


• Chitin is similar in structure to cellulose, but it contains nitrogen atoms, making it unique to fungi.


• The chitin in the cell wall of Rhizopus hypha helps to maintain the shape and integrity of the hyphae, allowing them to grow and penetrate substrates.


• In addition to chitin, the cell wall of Rhizopus hypha may also contain other components such as proteins and glucans, which contribute to its overall structure and function.

Overall, chitin is the primary component of the cell wall of Rhizopus hypha, providing strength and support to the fungal structure.

Ascomycetes are 'spore shooters'. They are fungi which produce microscopic spores inside special, elongated cells or sacs, known as 'asci', which give the group its name. They include most moulds, mildews, and yeasts, the fungal component of most lichens and penicillium.

The fungus that may cause disease in human beings is Aspergillus.
Aspergillus is a genus of fungi that can cause various diseases in humans. Here is a detailed explanation of why Aspergillus is the correct answer:
1. Aspergillus:
- Aspergillus is a common type of fungus that can be found in both indoor and outdoor environments.
- There are several species of Aspergillus, but the most common one that affects humans is Aspergillus fumigatus.
- It can cause a range of diseases in individuals with weakened immune systems, such as those with HIV/AIDS, organ transplant recipients, or individuals undergoing chemotherapy.
2. Aspergillosis:
- The diseases caused by Aspergillus are collectively known as aspergillosis.
- Aspergillosis can manifest in several forms, including allergic reactions, lung infections, sinus infections, and even systemic infections that can spread throughout the body.
3. Risk factors:
- Individuals with weakened immune systems are more susceptible to developing aspergillosis.
- Other risk factors include chronic lung diseases, such as cystic fibrosis or chronic obstructive pulmonary disease (COPD), and prolonged use of corticosteroid medications.
4. Symptoms:
- The symptoms of aspergillosis vary depending on the type and severity of the infection.
- Allergic reactions may cause symptoms like sneezing, runny nose, cough, and wheezing.
- Lung infections can lead to symptoms such as cough, chest pain, shortness of breath, and fever.
- Sinus infections can cause facial pain, nasal congestion, and discharge.
5. Diagnosis and treatment:
- Laboratory tests, imaging studies, and fungal cultures are often used to diagnose aspergillosis.
- Treatment typically involves antifungal medications, such as voriconazole or amphotericin B, to eliminate the fungal infection.
- In severe cases, surgical intervention may be necessary to remove infected tissue.
In conclusion, Aspergillus is a fungus that can cause diseases in humans, collectively known as aspergillosis. It is important to seek medical attention if you experience any symptoms associated with aspergillosis, especially if you have a weakened immune system or other risk factors.

Amphibians are those organisms which live on both land and in water. Bryophytes are called amphibians of the plant kingdom because these plants though live in soil but they need water for sexual reproduction. The sperm of bryophyte (antherozoids) are flagellate and need water to swim to the eggs. They are aquatic.

Azolla is a water fern that floats on the surface of fresh water ponds, rivers, and flooded fields in the tropics and subtropics of both the New and Old Worlds. It belongs to a derived group of ferns Azollaceae and is closely related to several other aquatic taxa such as Salvinia and Marsilea (11).

Gymnosperms do not have:
- Antheridium: Antheridium is the male reproductive structure found in bryophytes and pteridophytes, but not in gymnosperms. Gymnosperms have male cones that produce pollen grains.
- Archegonium: Archegonium is the female reproductive structure found in bryophytes and pteridophytes, but not in gymnosperms. Gymnosperms have female cones that contain ovules.
- Ovule: Ovules are the structures that contain the female gametophyte and eventually develop into seeds after fertilization. Gymnosperms have ovules that are exposed on the surface of the cones, unlike angiosperms where ovules are enclosed within the ovary.
- Egg: Eggs are the female gametes that are fertilized by the male gametes to form a zygote. Gymnosperms have eggs, but they are not produced within archegonia like in bryophytes and pteridophytes.
In summary, gymnosperms lack antheridia, archegonia, and enclosed ovules, although they do have eggs.

The correct answer is'C because in scientific name if a name comes from any scientist name than the symbol or name starts from capital letter and if it is given by some person than the name starts with small letter.

Echinodermata, spiny skinned animals such as sea stars, sea urchins, and sea cucumbers.

Specialized tissue for conduction of water in different plant groups:


(i) Thallophyta:
- Thallophyta includes algae and fungi.
- They do not possess specialized tissues for the conduction of water.
- Water moves through simple diffusion in thallophytes.
(ii) Bryophyta:
- Bryophyta includes mosses, liverworts, and hornworts.
- They also lack specialized tissue for water conduction.
- Water moves through simple diffusion in bryophytes.
(iii) Pteridophyta:
- Pteridophyta includes ferns, horsetails, and clubmosses.
- They have specialized tissue called xylem.
- Xylem is responsible for the conduction of water and minerals from roots to other parts of the plant.
(iv) Gymnosperms:
- Gymnosperms include plants like conifers, cycads, and ginkgo.
- They also have specialized tissue called xylem.
- Xylem helps in the conduction of water and minerals in gymnosperms.
Conclusion:
- Thallophyta and Bryophyta do not have specialized tissues for water conduction.
- Pteridophyta and Gymnosperms possess specialized tissue called xylem for the conduction of water.
- Therefore, the correct answer is (C) (iii) and (iv).

Cyanobacteria and archaebacteria belong to kingdom-Monera. Monerans are organisms without nucleus and cell organelles and are called prokaryotes.

Karl Von Linne and his involvement with the branch of science
Karl Von Linne, also known as Carl Linnaeus, was a renowned Swedish scientist who made significant contributions to the field of biology. He is best known for his work in taxonomy, the branch of science that deals with the classification and naming of organisms. Here's a detailed explanation of his involvement with this particular branch of science:
1. Taxonomy:
- Karl Von Linne is often referred to as the father of modern taxonomy.
- He developed a hierarchical system of classification, known as the Linnaean system, which is still widely used today.
- Linnaeus introduced the use of binomial nomenclature, which assigns a two-part scientific name to each species, consisting of the genus and species name.
- His system aimed to organize and categorize the vast diversity of living organisms based on their shared characteristics.
2. Contributions:
- Linnaeus traveled extensively, collecting and studying plants and animals from different parts of the world.
- He classified and described thousands of species, publishing numerous works on taxonomy and natural history.
- Linnaeus's classification system provided a standardized and universal language for scientists to communicate and identify organisms.
- His work laid the foundation for future advancements in the field of biology and helped establish a systematic approach to studying and understanding the natural world.
3. Impact:
- Linnaeus's contributions to taxonomy revolutionized the way scientists classify and organize living organisms.
- His system of naming and categorizing species continues to be the basis for biological classification.
- Linnaeus's work paved the way for further advancements in the field of biology and influenced generations of scientists.
- His ideas and methods are still taught and studied in biology classrooms worldwide.
In conclusion, Karl Von Linne, or Carl Linnaeus, was primarily involved with the branch of science known as taxonomy. His groundbreaking work in classification and naming of organisms has had a lasting impact on the field of biology.

It means the preventi... moreon of favoured races in the struggle for life published on 24 November 1859 is a work of scientific literature by Charles Darwin which is considered to be the foundation of evolutionary biology

The rhizome is the stem of the fern plant.