9th Class Science Improvement in food resources Improvement in Food Resources

Improvement in Food Resources

• Agriculture is the science of growing plants and raising animals useful to man.
• Science of growing vegetables, fruits and ornamental plants is called horticulture.
• The plants grown and tended or cared for in a field are known as crop plants or crops.
• There are two main seasons for cultivating crops in India. These are winter season and summer season crops.
• The crops grown in winter season are called Rabi crops and the crops grown in summer season are called Kharif crops.
• Wheat, barley, gram, pea, potato and mustard are rabi season crops while rice, maize, groundnut, soyabean, arhar, urad, moong, jowar, and cotton are kharif season crops.
• Nutrients which are required in relatively large quantity are called macronutrients while those required in small quantity are called micronutrients.
• The major sources of nutrients in the field are manures and fertilisers.
• Vermicomposting is composting with the help of earthworms.
• Accumulation of wastes and organic matter in the water body leads to excessive growth of phytoplankton and this in turn results into the depletion of free oxygen content in that water body. This phenomenon is called eutrophication.
• Biofertilisers are micro-organisms or biologically active products which are used to enrich soil fertility. Generally Rhizobium, Anabaena which are found in symbiotic association with plants like Legumes, Azolla, etc. are used as biofertilisers.
• Farming is a process of producing plants and animal products in a farm.
• Organic farming is a farming system in which fertilisers, herbicides or pesticides are replaced by manures, recycled farm wastes, and biofertilisers.
• Mixed farming is defined as the system of farming in which crop production is combined with the rearing of livestock.
• Mixed cropping is the practice of growing two or more crops simultaneously in the same field.
• Growing more than two crops in succession in a field during one year is called multiple cropping.
• The basic objective of mixed cropping is to achieve insurance against total crop failure under poor rainfall conditions.
• Intercropping is the practice of growing two or more crops simultaneously in the same field in rows.
• The practice of growing different crops in the same field alternately, in succession, is called crop rotation.
• Unwanted plants growing in a field are called weeds, and the process of removing weeds from a field is called weeding.
• The method of controlling living organisms by the use of other organisms is called biological control.

Commonly Asked Questions

• When green tomatoes turn red then:

(a) New chloroplast are made,

(b) Chromoplasts are changed into chloroplasts

(c) Chloroplasts are disintegrated and get converted into chromoplasts

(d) All of these

(e) None of these

Answer (C)

Explanation: When green tomatoes turn red then chloroplasts are disintegrated and get converted into chromoplasts. Chromoplasts absorb light energy and pass it on to chlorophyll in the chloroplasts.

• Which of the following organelles are the cells' garbage disposal system'?

(a) Peroxisomes              (b) Golgi complex

(c) Phagosomes              (d) Lysosomes

(e) None of these

Answer (D)

Explanation: Lysosomes are the cells of garbage disposal system because they help in disposal of unwanted materials.

• The smallest organelles in a cell are:

(a) Lysosomes                (b) Spherosomes

(c) Peroxysomes             (d) Ribosomes

(e) None of these

Answer (D)

Explanation: Ribosomos are smallest organelles found either attached to endoplasmic reticulum or freely in cytoplasm.

• The inner membrane of mitochondrion is usually highly convoluted forming a series of infolding known as:

(a) thylakoids                 (b) grana

(c) cristae                       (d) lamellae

(e) None of these

Answer (C)

Explanation: The inner membrane of mitochondria is usually highly convoluted forming a series of infolding known as cristae.

• Which of the following cell component is not directly involved in synthesis and secretion?

(a) Ribosome                      

(b) Rough endoplasmic reticulum

(c) Lysomsome                     

(d) Smooth endoplasmic reticulum

(e) None of these

Answer (C)

Explanation: Lysosome is not directly involved in synthesis and secretion.