NCERT Class 9 Science Solutions: Improvement in Food Resources

Question:

Animal Husbandry: The management and breeding of domestic animals, especially livestock. This includes practices aimed at improving the yield of products like meat, milk, eggs, wool, honey, and fish. Key aspects involve selecting superior breeds, providing proper nutrition and housing, disease prevention, and efficient harvesting.


The question asks for a common factor in poultry, fisheries, and bee-keeping for increasing production. All three are forms of animal husbandry aimed at producing specific resources for human consumption or use.

Poultry farming is concerned with raising domestic birds (like chickens, ducks, turkeys) for their meat and eggs. Increasing production involves selecting high-yielding breeds, optimizing feed, managing housing for better growth and egg-laying, and controlling diseases.

Fisheries involves the cultivation and harvesting of fish and other aquatic organisms. Increasing production can be achieved through aquaculture (fish farming), improved fishing techniques, sustainable management of fish stocks, and breeding programs for faster growth and disease resistance.

Bee-keeping (apiculture) is the practice of raising honey bees for their honey, beeswax, and pollination services. Increasing production involves maintaining healthy bee colonies, providing suitable habitats and nectar sources, managing diseases and pests, and harvesting honey efficiently.

The common thread across all these activities for increasing production is the application of scientific methods and management techniques to enhance the yield and efficiency of the respective animal or organism. This involves careful breeding, nutrition, health management, and environmental control tailored to the specific needs of poultry, fish, or bees.

Therefore, the common aspect for increasing production in poultry, fisheries, and bee-keeping is scientific management and breeding practices to enhance yield.

Question:

The question requires differentiating between three terms related to the harvesting and cultivation of aquatic organisms. The key concepts involve understanding the origin of the aquatic organisms (wild vs. cultivated), the environment from which they are obtained (natural waters vs. controlled environments), and the specific practices involved.


Capture fishing, mariculture, and aquaculture are all related to obtaining aquatic organisms, but they differ in their approach and origin:

Capture Fishing: This refers to the harvesting of wild aquatic animals from their natural habitats, such as oceans, seas, rivers, and lakes. The animals are not intentionally grown or managed by humans; instead, they are caught using various fishing methods.

Mariculture: This is a specialized form of aquaculture that specifically involves the cultivation of marine organisms (those living in saltwater). Mariculture takes place in marine environments, such as coastal waters, bays, or offshore areas, and involves raising species like fish, shellfish, and seaweeds.

Aquaculture: This is the broader term that encompasses the farming of aquatic organisms, including both freshwater and saltwater species. It involves raising aquatic animals and plants in controlled or semi-controlled environments. This can include inland ponds, tanks, raceways, and even cages in natural water bodies. Mariculture is a subset of aquaculture.

In essence:
Capture fishing is about catching wild animals.
Aquaculture is about farming aquatic animals and plants in controlled environments.
Mariculture is a specific type of aquaculture focused on marine (saltwater) organisms.

Question:

Understanding factors affecting food preservation, specifically during storage of grains. This involves identifying agents of spoilage and environmental conditions that promote spoilage.


Losses of grains during storage can occur due to a variety of biotic (living) and abiotic (non-living) factors.

Biotic factors include:
1. Pests: Rodents (rats, mice) can physically consume and contaminate grains with their droppings. Insects like weevils, moths, and beetles can infest grains, feeding on them and reducing their quantity and quality.
2. Microorganisms: Fungi (molds) and bacteria can grow on grains, especially in the presence of moisture. This leads to spoilage, loss of nutritional value, and the production of toxins.

Abiotic factors include:
1. Moisture: High humidity and inadequate drying of grains before storage create favorable conditions for the growth of insects and microorganisms, leading to spoilage and germination.
2. Temperature: High temperatures can accelerate insect activity and microbial growth.
3. Oxygen: While some oxygen is needed for respiration by grains and stored product insects, excessive oxygen in combination with other factors can contribute to spoilage.
4. Physical Damage: Improper handling and transport can lead to broken grains, which are more susceptible to insect and microbial attack.
5. Poor Storage Conditions: Inadequate ventilation, leaky storage structures, and improper packaging allow for moisture ingress, pest entry, and unfavorable temperature fluctuations.

Question:

Storage of grains involves keeping them in a condition that prevents spoilage and loss. This requires protection from various factors that can damage the stored produce.


Storage grain losses occur due to several biotic and abiotic factors.

Biotic factors are living organisms that cause damage. These include:
1. Pests: Insects like weevils, beetles, and moths lay eggs on grains, and their larvae feed on them, reducing the quantity and quality. Rodents like rats and mice consume and contaminate grains.
2. Microorganisms: Fungi (molds) and bacteria can grow on grains, especially if they are stored with high moisture content. This leads to spoilage, loss of nutritional value, and the production of toxins.

Abiotic factors are non-living environmental conditions that contribute to losses. These include:
1. Moisture: High humidity and damp storage conditions promote the growth of microorganisms and insects.
2. Temperature: High temperatures can accelerate the life cycle of insects and encourage microbial activity.
3. Physical damage: Improper handling during storage and transportation can lead to broken grains, making them more susceptible to pest and microbial attack.
4. Poor storage structures: Inadequate ventilation, leaks, and poor hygiene in storage facilities can create an environment conducive to spoilage and infestation.
5. Chemical changes: Over time, grains can undergo natural chemical changes that affect their quality and usability.

Question:

The question asks about the methods by which fish are obtained. This involves understanding human activities related to acquiring fish as a food source or for other purposes. Key concepts include natural sources of fish and human intervention.


Fish are obtained through two primary methods:

1. Natural Catching: This involves capturing fish from their natural habitats, such as oceans, seas, rivers, and lakes. The most common methods for natural catching include:
* Fishing: This is a broad term encompassing various techniques, including using nets (like trawl nets, gillnets, seine nets), lines and hooks (angling), traps, and spears. Commercial fishing often uses large boats and specialized equipment for mass capture, while recreational fishing uses simpler methods.
* Hunting: In some contexts, particularly historically or in specific cultures, fish might be hunted directly.

2. Aquaculture (Fish Farming): This involves the cultivation of fish in controlled environments. This can be done in:
* Ponds: Man-made or natural bodies of water where fish are raised.
* Cages or pens: Structures placed in natural water bodies (lakes, rivers, coastal areas) where fish are confined and fed.
* Recirculating Aquaculture Systems (RAS): Advanced systems that control water quality and re-use water, often land-based.

Therefore, fish are obtained either by catching them from the wild or by farming them.

Question:

Plant nutrition, soil fertility, macronutrients, micronutrients, organic matter, humus, soil health.


Manures and fertilizers are used in fields to enrich the soil with essential nutrients that plants need for healthy growth. Over time, crops absorb these nutrients, depleting the soil’s natural reserves.

Manures are organic substances derived from decomposed animal waste, plant residues, and other organic matter. They improve soil structure, increase water retention, and release nutrients slowly, providing long-term benefits. They are rich in a wide range of nutrients and also add organic matter to the soil, which enhances its fertility and biological activity.

Fertilizers are inorganic or organic compounds that contain specific plant nutrients, often in concentrated forms. They are typically rich in macronutrients like nitrogen (N), phosphorus (P), and potassium (K), which are required in large amounts by plants. Fertilizers are used to quickly replenish depleted nutrient levels and ensure plants receive the specific elements they need for optimal growth, flowering, and fruiting.

In summary, both are used to:
1. Provide essential nutrients (macronutrients and micronutrients) for plant growth.
2. Replenish nutrients depleted by previous crops.
3. Improve soil fertility and productivity.
4. Enhance plant vigor, yield, and quality.

Question:

The question is about improving cattle breeds. This involves understanding what “improving breeds” means in agriculture and the biological processes involved. Key concepts include genetics, selective breeding, and desired traits in livestock.


The commonly used method for improving cattle breeds is selective breeding.

This method is used because it allows for the targeted enhancement of desirable traits in cattle over generations. Selective breeding involves identifying animals with specific beneficial characteristics, such as:

* Higher milk yield: For dairy cattle.
* Better meat quality and faster growth rate: For beef cattle.
* Disease resistance: To reduce losses and improve overall herd health.
* Adaptability to local climate and conditions: To ensure survival and productivity in specific environments.

By choosing only the best individuals with these desired traits to reproduce, breeders can gradually increase the frequency of the genes responsible for these traits in the offspring. Over time, this leads to a more genetically improved population of cattle that are more productive, healthier, and better suited to their purpose. This process is efficient and allows for gradual, predictable improvements compared to natural selection.

Question:

High yield crop production relies on optimizing various factors that influence plant growth and development. Key concepts include understanding soil fertility management, water management, pest and disease control, and appropriate seed selection.


One method of crop production that ensures high yield is the use of improved varieties of seeds. These seeds are often developed through scientific breeding techniques to possess desirable characteristics such as higher yield potential, resistance to pests and diseases, and better adaptability to local environmental conditions. When farmers plant these improved varieties, they are starting with a genetic advantage that significantly contributes to a higher output per unit area. Alongside improved seeds, other practices like proper irrigation, judicious use of fertilizers, and timely pest and disease management are crucial to fully realize the potential of these high-yielding varieties. For instance, a hybrid variety of wheat might have a higher grain production capacity, but it will only achieve this high yield if it receives adequate water and nutrients, and is protected from common wheat rusts. Therefore, the selection of improved seeds is a foundational step towards achieving high crop yields.

Question:

The core concept is understanding the role of poultry in the food chain and its economic and nutritional significance, specifically its ability to convert waste products into valuable food. Key terms include: ‘poultry’, ‘efficient converter’, ‘low fibre food stuff’, ‘unfit for human consumption’, and ‘highly nutritious animal protein food’.


The statement highlights the remarkable efficiency of poultry farming in India. It means that chickens and other poultry animals are adept at consuming food materials that humans cannot digest or utilize effectively, such as agricultural byproducts, kitchen scraps, and certain plant matter that is high in fiber. Instead of these materials going to waste, poultry can process them and, through their biological functions, transform them into high-quality animal protein in the form of eggs and meat. This process is economically beneficial as it reduces waste and provides a readily available source of protein for human consumption. It also contributes to food security and offers a sustainable way to produce nutritious food. This efficiency makes poultry a crucial component of India’s agricultural and nutritional landscape.

Question:

This question requires knowledge about the nutritional components found in common food groups like cereals, pulses, fruits, and vegetables. Specifically, it’s about identifying the main types of nutrients these foods provide to our bodies.


Cereals like rice, wheat, and maize are primarily sources of carbohydrates, which provide energy. They also contain some proteins and dietary fiber.
Pulses (legumes) such as lentils, beans, and peas are excellent sources of proteins and dietary fiber. They also offer carbohydrates and some vitamins and minerals.
Fruits are rich in vitamins, minerals, and natural sugars (carbohydrates) for energy. They also provide dietary fiber and antioxidants.
Vegetables are packed with vitamins, minerals, and dietary fiber. They also contain carbohydrates and some water.

Therefore, from cereals, pulses, fruits, and vegetables, we get carbohydrates, proteins, vitamins, minerals, and dietary fiber.

Question:

Plants primarily obtain nutrients from the soil. These nutrients are essential for their growth and survival. The process involves absorption of dissolved minerals by the roots.


Plants acquire essential nutrients primarily through their root systems from the soil. These nutrients are minerals dissolved in water. The roots have specialized structures called root hairs that significantly increase the surface area for absorption. As water is absorbed by the roots, these dissolved mineral nutrients are also taken into the plant. These nutrients are then transported throughout the plant via the xylem, a vascular tissue, to support various physiological processes like photosynthesis, growth, and reproduction. Besides soil, some nutrients can also be absorbed from the atmosphere (like carbon dioxide for photosynthesis) or through other means. However, the majority of mineral nutrients are sourced from the soil.

Question:

Genetic manipulation refers to the direct alteration of an organism’s genetic material (DNA) to change its characteristics. This involves techniques that allow scientists to add, remove, or modify genes.


Genetic manipulation, also known as genetic engineering or recombinant DNA technology, is a set of techniques used to directly alter the genetic makeup of an organism. It involves modifying the DNA of an organism by introducing new genes, removing existing ones, or changing the sequence of genes. This is achieved using various molecular biology tools and enzymes that can cut, paste, and copy DNA segments. The primary goal is to introduce desirable traits into an organism or to remove undesirable ones, leading to a change in its phenotype (observable characteristics). For example, it can be used to make crops resistant to pests, produce insulin in bacteria, or develop disease-resistant animals.

Question:

Nutrients are substances essential for growth and life. They are broadly classified based on the quantity required by the body.


Macronutrients are nutrients that the body needs in large amounts. They are called macronutrients because the Greek prefix “macro-” means “large.” These nutrients provide energy (calories) and are essential for building and repairing tissues, and for various metabolic processes. The primary macronutrients are carbohydrates, proteins, and fats. In contrast, micronutrients are needed in much smaller quantities.