Economic Importance of Plants Practice Questions
19 free Economic Importance of Plants practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following algae is widely used as a food supplement by space travellers due to its high protein content?
- A Chlorella
- B Spirogyra
- C Volvox
- D Fucus
Correct answer: Chlorella
Chlorella and Spirulina are unicellular algae that are exceptionally rich in proteins. They are utilized as food supplements even by space travellers to maintain nutrition in compact forms.
Agar-agar, a commercial product used to grow microbes and in preparations of ice-creams and jellies, is obtained from:
- A Gelidium and Gracilaria
- B Chlamydomonas and Volvox
- C Porphyra and Laminaria
- D Sargassum and Dictyota
Correct answer: Gelidium and Gracilaria
Agar is a hydrocolloid obtained from certain red algae like Gelidium and Gracilaria. It is indispensable in laboratories as a solidifying agent for culture media.
Algin, a water-holding substance (hydrocolloid), is extracted from which group of algae?
- A Red algae
- B Green algae
- C Blue-green algae
- D Brown algae
Correct answer: Brown algae
Brown algae produce large amounts of algin, a hydrocolloid with excellent water-holding capacity. It is used commercially in various industries, including food and textiles.
Carrageen is a hydrocolloid commercially produced from which of the following?
- A Red algae
- B Brown algae
- C Green algae
- D Diatoms
Correct answer: Red algae
Carrageen is a sulfated polysaccharide extracted from red seaweeds. It is widely used in the food industry for its gelling, thickening, and stabilizing properties.
Many species of which of the following genera are among the 70 species of marine algae used as food?
- A Porphyra, Laminaria and Sargassum
- B Spirogyra, Ulothrix and Cladophora
- C Chlorella and Chlorococcum
- D Volvox and Eudorina
Correct answer: Porphyra, Laminaria and Sargassum
Porphyra, Laminaria, and Sargassum are significant marine algae consumed as food in many coastal countries. They provide essential minerals and vitamins to the diet.
Sphagnum, a moss, provides peat that has long been used as fuel and as:
- A A natural source of antibiotics
- B Packing material for live plants
- C A primary producer in deep water
- D A decorative plant for gardens
Correct answer: Packing material for live plants
Sphagnum has a remarkable capacity to hold water, making it an ideal packing material for transporting living plants. Its partially decomposed form, peat, is also used as a fuel source.
What is the ecological importance of mosses in preventing soil erosion?
- A They have deep tap roots in the soil
- B They form dense mats covering the soil
- C They secrete chemicals that harden the soil
- D They attract animals that compact the soil
Correct answer: They form dense mats covering the soil
Mosses form dense, carpet-like mats on the ground which significantly reduce the impact of falling rain. This prevents the topsoil from being washed away, thereby reducing soil erosion.
Which plant group was the first to possess vascular tissues and is frequently grown as ornamentals or used for medicinal purposes?
- A Bryophytes
- B Pteridophytes
- C Gymnosperms
- D Monocotyledons
Correct answer: Pteridophytes
Pteridophytes, such as ferns and horsetails, are the first terrestrial plants to evolve xylem and phloem. They are valued economically for their aesthetic appeal as ornamentals and their use in traditional medicine.
Pteridophytes like Selaginella and Salvinia are often used as:
- A Biofertilizers
- B Soil binders
- C Fuel sources
- D Timber plants
Correct answer: Soil binders
Many pteridophytes play a crucial role as soil binders, protecting the land from degradation. Some specific aquatic ferns like Azolla are also used as bio-fertilizers, though 'soil binder' is a general economic feature of the group.
Which of the following gymnosperms is a source of high-quality timber used in construction?
- A Cycas
- B Cedrus
- C Gnetum
- D Ephedra
Correct answer: Cedrus
Cedrus, commonly known as Deodar, is a majestic gymnosperm found in the Himalayas. Its wood is highly durable, rot-resistant, and widely used for construction and making railway sleepers.
Sago, a starch-rich food, is often obtained from the stem of which plant?
- A Pinus
- B Cycas
- C Cedrus
- D Sequoia
Correct answer: Cycas
Sago is extracted from the pith of the stem of Cycas revoluta and other related species. It is a significant source of carbohydrates in many parts of the world.
Turpentine oil and resin are commercially obtained from:
- A Angiospermic herbs
- B Ferns
- C Red algae
- D Pinus
Correct answer: Pinus
Species of Pinus produce resins that are distilled to yield turpentine oil. These products are extensively used in the paint, varnish, and chemical industries.
Chilgoza, an edible dry fruit (nut), is the seed of:
- A Cycas circinalis
- B Cedrus deodara
- C Ginkgo biloba
- D Pinus gerardiana
Correct answer: Pinus gerardiana
Pinus gerardiana, known as the Chilgoza pine, produces edible seeds that are highly nutritious and commercially sold as dry fruits. They are a staple in the Himalayan regions.
Which gymnosperm yields an alkaloid drug used as a bronchodilator to treat asthma and respiratory ailments?
- A Ephedra
- B Taxus
- C Sequoia
- D Pinus
Correct answer: Ephedra
Ephedrine is an alkaloid extracted from the green stems of Ephedra. It acts as a bronchodilator and is used in medicines to treat asthma, hay fever, and common colds.
Angiosperms are the dominant plant group in modern ecosystems. Which best describes their economic importance?
- A They are the primary source of peat and agar
- B They are valued mainly as ornamental plants
- C They are important chiefly as a source of timber
- D They provide food, fodder, fuel, and medicines
Correct answer: They provide food, fodder, fuel, and medicines
Angiosperms are the primary source of food (cereals, fruits, vegetables), fodder, fuel, medicines, timber, fibers, oils, and various industrial raw materials, making them the most economically important plant group.
The roots of which gymnosperm are used to harbor nitrogen-fixing cyanobacteria, indirectly helping in soil fertility?
- A Pinus
- B Cedrus
- C Ginkgo
- D Cycas
Correct answer: Cycas
Cycas has specialized coralloid roots that live in symbiosis with N2-fixing cyanobacteria. This relationship helps the plant thrive in nutrient-poor soils and enriches the surrounding environment with nitrogen.
An important anti-cancer chemotherapy drug is obtained from the bark of which plant?
- A Pinus
- B Cycas
- C Eucalyptus
- D Taxus
Correct answer: Taxus
Taxol is a chemotherapy medication used to treat various types of cancers. It was originally discovered in the bark of the Pacific Yew (Taxus brevifolia), a gymnosperm.
Which of the following provides the largest amount of oxygen to the atmosphere among plant groups?
- A Rainforest trees
- B Cereal crops
- C Marine algae
- D Mosses
Correct answer: Marine algae
Marine algae and phytoplankton are responsible for a vast majority of the oxygen produced via photosynthesis globally. Their sheer biomass in the oceans makes them the largest oxygen contributors.
Which of the following is known as 'Stonewort' and helps in the deposition of calcium carbonate?
- A Ulva
- B Riccia
- C Chara
- D Funaria
Correct answer: Chara
Chara is a green alga found in lime-rich waters. It becomes encrusted with calcium carbonate, earning it the name 'Stonewort', and plays a role in marl formation in ponds.