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The correct answer is Statement (I) is false but Statement (II) is true.

Key Points

Statement I: Natural fibres like cotton, wool, silk, nylon are obtained from plants or animals is false because,-

• Natural fibres come from plants and animals, while nylon is a synthetic fibre.
• Cotton and linen are examples of natural fibres obtained from plants.
• Wool and silk are natural fibres derived from animals; wool comes from sheep, and silk comes from silkworms.
• Nylon, however, is a synthetic fibre made through chemical processes by humans and not obtained from natural sources

Statement II: Synthetic fibres are made by human beings, that is why these are called synthetic or man-made fibres is true.

• Synthetic fibres are artificially produced through chemical processes in laboratories and industries.
• Some common examples of synthetic fibres include nylon, polyester, and acrylic.
• These fibres are designed to mimic the properties of natural fibres but often come with enhanced durability and other specific characteristics.

Additional Information

• Natural fibres:
• Sources: Derived from plants (e.g., cotton) or animals (e.g., wool).
• Properties: Biodegradable, eco-friendly, and often comfortable to wear.
• Examples: Cotton, wool, silk, jute, and linen.
• Synthetic fibres:
• Sources: Man-made through chemical synthesis.
• Properties: Durable, versatile, often non-biodegradable, and can be engineered for specific uses.
• Examples: Nylon, polyester, acrylic, and rayon.

Correct Answer: (A) and (R) both are true and (R) is the correct explanation of (A).

Key Points

• Assertion (A): Some micro-organisms cause diseases in human beings, plants and animals is true because:
• Micro-organisms, including bacteria, viruses, fungi, and protozoa, are known to cause various diseases in humans, such as the flu, tuberculosis, and malaria.
• Plants are also susceptible to diseases caused by pathogens such as fungi (e.g., rusts, smuts, and molds), bacteria (e.g., bacterial wilt), and viruses (e.g., tobacco mosaic virus).
• Animals can be affected by micro-organisms causing diseases like foot-and-mouth disease in cattle and avian influenza in birds.
• Reason (R): Such disease causing micro-organisms are called pathogens is true because:
• Pathogens are specifically defined as micro-organisms that can cause disease in their hosts, a category that includes bacteria, viruses, fungi, and parasites.
• The term 'pathogen' is universally used in the field of microbiology and medicine to describe any organism that can induce pathological conditions in humans, animals, or plants.

Additional Information

• Micro-organisms can enter hosts through various routes such as inhalation, ingestion, or through wounds, leading to different types of infections and diseases.
• Understanding the nature of pathogens and how they cause disease is crucial for developing treatments, vaccines, and preventive measures in both human and veterinary medicine, as well as in agriculture for protecting crops.

Correct Answer: (A) and (R) both are true and (R) is not the correct explanation of (A).

Key Points

• Assertion (A): Animals including humans cannot make their own food is true because:
• Animals, including humans, are heterotrophic, meaning they must consume organic matter to obtain their nutrients because they cannot synthesize their own food from inorganic substances like autotrophic organisms (e.g., plants).
• Unlike plants and some bacteria that use photosynthesis or chemosynthesis to create their own food, animals rely on digesting food sourced from other organisms.
• Reason (R): Humans get their food from both plants as well as animals is true because:
• Humans are omnivores, meaning they consume a variety of foods derived from both plant and animal sources to meet their nutritional needs.
• Plant-based foods include fruits, vegetables, grains, and legumes, whereas animal-based foods include meat, dairy, and eggs.
• The relationship:
• While both statements are individually true, Reason (R) does not explain why Assertion (A) is true.
• The inability of animals, including humans, to make their own food is due to a lack of photosynthetic parts and processes (like chlorophyll in plants), meaning they must rely on external food sources.
• This is a biological limitation.
• Reason (R) merely states that humans acquire their food from both plants and animals, which describes a dietary practice but does not explain the fundamental biological reason behind why they cannot synthesize food themselves.
• Thus, the correct explanation would consider the biological limitations (such as the absence of photosynthesis). Since (R) does not address this biological reason and merely states where humans get their food from, it does not correctly explain (A).

Additional Information

• Autotrophs, such as plants, produce their own food through processes like photosynthesis by converting sunlight, carbon dioxide, and water into glucose and oxygen.
• Heterotrophs depend on organic compounds produced by other organisms for their energy and nutritional requirements.
• Understanding these fundamental distinctions between autotrophic and heterotrophic organisms is essential in ecology to comprehend energy flow and nutrient cycles in ecosystems.
• Human nutrition encompasses a wide range of food sources, balancing plant and animal products to obtain essential nutrients such as carbohydrates, proteins, fats, vitamins, and minerals necessary for healthy body functions.

The correct code is Only (A), (B) and (D)

Key Points

• Process of removing weeds is called weeding. This statement is correct.
• Weeding is the agricultural practice of removing unwanted plants (weeds) that compete with crops for nutrients, sunlight, and space.
• It helps in the better growth of crops by reducing competition.
• **The process of removing seeds from the chaff of harvested crop is called threshing.**This statement is correct.
• Threshing is the process of beating the harvested crop to separate the grain or seeds from the chaff.
• It is an essential post-harvest process to obtain clean seeds for consumption or storage.
• Cutting of crop after maturing is also called weeding. This statement is incorrect.
• Cutting of crop after maturing is called harvesting.
• Harvesting is the process of gathering mature crops from the fields once they are ready for consumption or sale.
• Weeding refers to removing unwanted plants (weeds), not the main crop.
• Supplying of water at regular time and interval is called irrigation. This statement is correct.
• Irrigation involves applying water to crops at required intervals to assist in their growth.
• It is vital in regions with irregular rainfall to ensure crops receive sufficient water throughout their growth periods

The correct answer is Ovary.

Explanation:

• After fertilisation, the flower develops into a fruit.
• Fruits can be dry (mustard, groundnut) or fleshy (orange, mango).
• A mature ovule and seed are found in the dry and fleshy part of a fruit.
• The flower's female reproductive part matures into a true fruit.
• A true fruit is one that develops from only a fully matured and ripened ovary.
• The ovule, which is located inside the ovary, produces the seeds of fruit.
• Some examples of true fruit are Watermelon, mango, lemon, kiwi, blueberry, plums etc.

Additional Information 

Fruits that develop from ovary and the thalamus or other part of the flower are known as false fruits.

Example: apple, strawberry

Correct Answer: (A) is true but (R) is false.

Key Points

• Assertion (A): Sandy soil is well aerated is true because:
• Sandy soil has large particles and large pore spaces, which allows for good air circulation and prevents water from clogging the soil.
• This characteristic makes sandy soil well-draining and well aerated, which is beneficial for the roots of certain types of plants that need good air exchange in the soil.
• Reason (R): The sand particles of sandy soil are very small is false because:
• Sand particles are actually larger than those of silt or clay. The larger particle size results in larger spaces between particles, contributing to better aeration and drainage in sandy soil.
• Small particles are characteristics of clay soil, not sandy soil. Clay soils have poor aeration due to the closely packed small particles.

Additional Information

• Sandy soils are commonly found in deserts and near riverbanks and have a gritty texture.
• These types of soils are often low in nutrients and do not hold water well, which can be a disadvantage for plant growth unless supplemented with organic material.
• Soil structure is one of the key factors affecting water retention, aeration, and nutrient availability for plants, with sandy, loamy, and clay soils each having distinct properties and uses in agriculture and gardening.
• In agricultural practices, the addition of organic matter can improve the water-holding capacity of sandy soils, making them more fertile and better suited for crop production.

The correct code is :Air expands on heating

Key Points

• Moving wind is called air. This statement is incorrect.
• Air is a mixture of gases that make up the Earth's atmosphere.
• When air moves, it is specifically referred to as wind, not the generic term 'air'.
• Air expands on heating. This statement is correct.
• When air is heated, its molecules move faster and spread out, causing the air to expand.
• This principle is used in hot air balloons, where heating air inside the balloon causes it to expand and become less dense than the cooler air outside, allowing it to rise.
• Air moves from the region of low air pressure to high air pressure. This statement is incorrect.
• Air typically moves from regions of high air pressure to low air pressure.
• This movement is due to the pressure gradient force, which causes air to flow from areas of higher pressure to areas of lower pressure in an attempt to equalize the pressure differences.
• This phenomenon is responsible for wind and weather patterns on Earth.

The correct answer isStatement (I) and (II) both are true.

Key Points 

Statement (I): Diarrhoea is not a fatal disease.

• Diarrhoea is a condition that is characterized by the passage of loose or watery stools, often accompanied by abdominal cramps, bloating, and nausea.
• While diarrhoea can be uncomfortable and disruptive, it is usually not a fatal disease, particularly in developed countries where access to medical care and clean water is readily available..

Statement (II): Diarrhoea leads to loss of water and salts from the body.

• Diarrhoea is caused by various factors, including bacterial, viral, and parasitic infections, as well as food intolerances and other underlying medical conditions.
• Regardless of the cause, diarrhoea can lead to the loss of water and salts from the body, which can result in dehydration and electrolyte imbalances.
• During a diarrhoeal episode, water and electrolytes are lost through the stool, leading to a decrease in blood volume and blood pressure.
• This can result in symptoms such as dizziness, fatigue, and muscle cramps.

In summary, both statements (I) and (II) are true.

The correct answer is they do not get nitrogen from the soil.

Key Points

• The pitcher plant performs photosynthesis which makes it an autotrophic plant but it has also a partial heterotrophic mode of nutrition because pitcher plant grows on nitrogen-deficient soil.
• Carnivorous plants obtain the essential nutrients from the heterotrophs.

Additional Information 

• The pitcher plant is an insectivorous plant
• It has a Pitcher-like structure that is the modified part of the leaf.
• The apex of the leaf forms a lid that can open and close the mouth of the pitcher.
• Inside the pitcher, there are hairs that are directed downwards.
• When an insect lands in the pitcher, the lid closes and the trapped insect gets entangled into the hair.
• The insect is digested by the digestive juices secreted in the pitcher.
• It can trap and eat frog, insects and even mice.
• It is found in Australia, Indonesia and Meghalaya in India.
• It has a pitcher-like shape and the mouth is covered by a leaf.
• It has a special smell that attracts insects to it, which get trapped and can't get out.

Thus, the pitcher plant is an insectivorous plant.

The correct answer is  (A), (B), and (D).

Key Points

About the Changpa tribe:

• Changpa is a nomadic tribe found in Ladakh.
• They stay high up on these mountains in very difficult conditions.
• Their goats and sheep are most important to them.
• Through these goats and sheep, they obtain meat to eat, wool to wear, skin for tents.
• They make the famous pashmina shawl through these goats.
• A pashmina shawl is very thin yet very warm.
• The Changpa tribe is known for making pashmina shawls.
• It is believed that a pashmina shawl is as warm as six sweaters.
• They live in a big cone-shaped tent called Rebo.
• Near the Rebo, they have a place to keep sheep and goats called Lekha.
• The walls of a lekha are made of stones.

​

Thus,

(A) Changpa are nomadic people: True

(B) Goats are their most important treasure: True

(C) This tribe is used to staying at a single place: False

(D) Changpa rear special kind of goats from whom the world famous Pashmina wool is made: True