Question
Which of the following is not an objective of biofortification in crops? [NEET 2021]
(a) Improve protein content
(b) Improve resistance to diseases
(c) Improve vitamin content
(d) Improve micronutrient and mineral content
Answer/Explanation
Ans. (b)
Biofortification is the method developed to produce crops with high level of vitamins, proteins and minerals to improve public health. Improving resistance to disease is not the objective of biofortification hence option(b) is correct.
Question
Match the List -I with List – II.
Choose tho correct answer from the options given below. [NEET 2021]
A B C D
(a) 3 4 2 1
(b) 2 1 4 3
(c) 3 4 1 2
(d) 4 3 2 1
Answer/Explanation
Ans. (b)
(A) $-2),(B)-(1),(C H(4),(D)-(3)$
Pomato is the potato and tomato hybrid.
Pomato can be formed by somatic hybridisation.
The mechanism by which two separate species of plant protoplasts fuse together to form hybrid is known as somatic hybridisation.Totipotency is the basis of tissue culture. Cells from growing root tips or shoot tips or any other growing part can be grown in nutrient medium under sterilised condition. Afterwards, these cells divides and grow into a mass of tissue called callus.
Meristem culture is one of the most widely used methads for virus elimination from infected plants and production of virus-free plants. Apical meristem culture is a proven means of clonal propagation and also for eliminating viruses from infected plants. The plants raised through micropropagation are called somaciones because they are genetically identical to the original plant from which they were grown. It helps in producing plants that are disease and pest resistant.
Question
Mutations in plant cells can be induced by [NEET 2021]
(a) kinetin
(b) infrared rays
(c) gamma rays
(d) zeatin
Answer/Explanation
Ans. (c)
Mutation is defined as the process by which genetic changes are created via changes in the sequences of bases present within genes. This results in the formation of a new trait or character not found in the parental type.
Thus, it is possible to induce mutations with the help of various chemicals or radiations such as gamma radiations artificially and then selecting and using plants with desirable traits as a source in breeding. This process is termed as mutational breeding.
Question
In mung bean, resistance to yellow mosaic, virus and powdery mildew were brought about by [NEET (Odisha) 2019]
(a) mutation breeding
(b) biofortification
(c) tissue culture
(d) hybridisation and selection
Answer/Explanation
Ans. (a)
In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutation breeding. Mutation breeding is the process of exposing seeds to chemicals or radiation in order to generate mutants with desirable traits to be bred with other cultivars.
Question
Which of the following is true for Golden rice? [NEET 2018]
(a) It is pest resistant, with a gene from Bacillus thuringiensis
(b) It is drought tolerant, developed using Agrobacterium vector
(c) It has yellow grains, because of a gene introduced from a primitive variety of rice
(d) It is vitamin-A enriched, with a gene from daffodil
Answer/Explanation
Ans. (d)
Statement that Golden rice is vitamin-A enriched, with a gene from daffodil is true. Goiden rice is genetically engineered variety of rice to biosynthesise $\beta$-carotene which is a precursor of vitamin-A. It contains psy gene (phytoene synthase) which is derived from daffodil. Other statements are not true for golden rice. The correct information about the statements is as follows The grains of golden rice appear yellow due to high level of $\beta$-caratene in it. Golden rice is neither drought tolerant nor pest resistant.
Question
What triggers activation of protoxin to active $B t$ toxin of Bacillus thuringiensis in bollworm? [NEET (National) 2019]
(a) Moist surface of midgut
(b) Alkaline $\mathrm{pH}$ of gut
(c) Acidic pH of stomach
(d) Body temperature
Answer/Explanation
Ans. (b)
Alkaline $\mathrm{pH}$ af gut triggers activation of protoxin to active Bt toxin of Bacillus thuringiensis in bollworm. The inactive protoxins contain toxic insecticidal protein crystals.
When the alkaline pH of insect gut solubilises the crystals, the activated toxin binds to the epithelial cells af the midgut and creates pores. It causes the cell to swell and burst, eventually causing the death of insect.
Question
Select the incorrect statement. [NEET (National) 2019]
(a) Inbreeding is essential to evolve purelines in any animal
(b) Inbreeding selects harmful recessive genes that reduce fertility and productivity
(c) Inbreeding helps in accumulation of superior genes and elimination of undesirable genes
(d) Inbreeding increases homozygosity
Answer/Explanation
Ans. (b)
Statement that inbreeding selects harmful recessive genes that reduce fertility and productivity is incorrect. The correct information regarding the statement is as follows
Inbreeding does not select harmful recessive genes. It exposes harmful recessive genes that are eliminated by selection and thus reduces fertility and productivity. This is called inbreeding depression. Statements in other options are correct.
Question
A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called [NEET 2016, Phase I]
(a) contour farming
(b) strip farming
(c) shifting agriculture
(d) ley farming
Answer/Explanation
Ans. (d)
Ley farming is a system of rotating crops with legumes or grass pasture in order to improve soil structure and fertility and also to disrupt pest and disease life cycles.
Question
In plant breeding programmes, the entire collection (of plants/seeds) having all the diverse alleles for all genes in a given crop is called [NEET 2013]
(a) selection of superior recombinants
(b) cross-hybridisation among the selected parents
(c) evaluation and selection of parents
(d) germplasm collection
Answer/Explanation
Ans. (d)
It is called germplasm collection. Selection of superior recombinants means selection of the best plant from the whole lot by visual examination and collecting their seeds for growing in field. Cross hybridisation is the method of combining the characters of different plants together. The selection and evaluation are the main steps of hybridisation.
Question
Consider the following four statements (I-IV) and select the option which includes all the correct ones only.
I. Single cell Spirulina can produce large quantities of food rich in protein, minerals, vitamins, etc.
II. Body weight-wise the microorganism Methylophilus methylotrophus may be able to produce several times more proteins than the cows per day.
III. Common button mushrooms are a very rich source of vitamin-C.
IV. A rice variety has been developed which is very rich in calcium. [CBSE AIPMT 2012]
(a) Statements III and IN
(b) Statements I, III and IV
(c) Statements II, III and IV
(d) Statements I and II
Answer/Explanation
Ans. (d)
Out of the given statements (I) and (ii) are correct as single cell Spirulina can produce large quantities of food rich in protein, minerals, vitamins, etc. And body weight-wise the microorganism Methylophilus methy lotrophus may be able to produce several times more proteins than cows per day.
Question
‘Jaya’ and ‘Ratna’ developed for green revolution in India are the varieties of [CBSE AIPMT 2011]
(a) maize
(b) rice
(c)wheat
(d) bajra
Answer/Explanation
Ans. (b)
‘Jaya’ and ‘Ratna’ are better yielding semi-dwarf varieties of rice developed in India for green revolution.
Question
‘Himgiri’ developed by hybridisation and selection for disease resistance against rust pathogens is a variety of [CBSE AIPMT 2011]
(a) chilli
(b) maize
(c) sugarcane
(d) wheat
Answer/Explanation
Ans. (d)
‘Himgirry is a variety of wheat. It is resistant to leaf and stripe rust, hill bunt. diseases.
Question
Consider the following statements (1-IV) about organic farming. [CBSE AIPMT 2011]
I. Utilises genetically modified crops like Bt cotton.
II. Uses only naturally produced inputs like compost.
III. Does not use pesticides and urea.
IV. Produces vegetables rich in vitamins and minerals.
Which of the above statements are correct?
(a) II, III and IV
(b) III and IV
(c) II and III
(d)I and II
Answer/Explanation
Ans. (c)
Qut of the given statements (II) and (III) are correct as organic farming is the form of agriculture that relies on techniques such as crop rotation, green manure, compost and biological pest control to maintain soil productivity and contral pest on a farm. Organic farming excludes or strictly limits the use of manufactured fertilisers, pesticides (which include herbicides, insecticides and fungicides) plant growth regulators such as hormones, food additives and genetically modified organisms.
Question
Breeding of crops with high levels of minerals, vitamins and proteins is called [CBSE AIPMT 2010]
(a) somatic hybridisation
(b) biofortification
(c) biomagnification
(d) micropropagation
Answer/Explanation
Ans. (b)
Breeding of crops with higher levels of vitamins and minerals or higher protein and healthier fats is called biofortification. This is the most practical aspect to improve the health of the people.
Question
Which one of the following is linked to the discovery of Bordeaux mixture as a popular fungicide? [CBSE AIPMT 2008]
(a) Loose smut of wheat
(b) Black rust of wheat
(c) Bacterial leaf blight of rice
(d) Downy mildew of grapes
Answer/Explanation
Ans. (d)
Bordeaux mixture is the first inorganic fungicide which was developed by RMA Millardet(1882] against downy mildew (Plasmopora viticala) of grape-vine at the University of Bordeaux. It consists of copper (Ii) sulphate (CuSO, ) slaked lime and water.
Question
Consider the following four measures (1-4) that could be taken to successfully grow chickpea in an area where bacterial blight disease is common.
I. spray with Bordeaux mixture.
11. control of the insect vector of the disease pathogen.
III. use of only disease-free seeds.
IV. use of varieties resistant to the disease.
Which two of the above measures can control the disease? [CBSE AIPMT 2008]
(a) III and IV
(b) I and IV
(c) II and IIII
(d) I and III
Answer/Explanation
Ans. (b)
Bacterial blight of chickpea is caused by bacterium Xanthomonos campestris. The stems and the leaves of infected plant give blighted or burnt up appearance. Control measures includes roguing, 3-year crop rotation, disease-free seeds, spray of copper fungicides (Bordeaux mixture) and antibiotics besides sowing disease resistant varieties.
Question
Farmers in a particular region were concerned that pre-mature yellowing of leaves of a pulse crop might cause decrease in the yield. Which treatment could be most beneficial to obtain maximum seed yield? [CBSE AIPMT 2006]
(a) Frequent irrigation of the crop
(b) Treatment of the plants with cytokinins along with a small dose of nitrogenous fertiliser
(c) Removal of all yellow leaves and spraying the remaining greenleaves with $2,4,5$-trichlorophenoxy acetic acid
(d) Application of iron and magnesium to promote synthesis of chlorophyll
Answer/Explanation
Ans. (d)
If a pulse crop possesses premature yellowing of leaves and decrease in yield an application of magnesium and iron to promote synthesis of chlorophyli may become most beneficial to overcome the problem and to obtain maximum seed yield.
Magnesium is an important part of ring structure of chlorophyll molecule and its deficiency causes chlorosis and premature leaf abscission.
In iron deficiency also, the leaves become chloratic because iran is required for the synthesis of some of the chlorophyll protein complexes in the chloroplast.
Question
In maize, hybrid vigour is exploited by [CBSE AIPMT 2006]
(a) inducing mutations
(b) bombarding the protoplast with DNA
(c) crossing of two inbred parental lines
(d) harvesting seeds from the most productive plants
Answer/Explanation
Ans. (c)
Hybrid vigour has been commercially exploited in different commercial crops like maize, sorghum, bajra, tomato, sugarbeet. Hybridisation or crossing of two unrelated individuals or parental lines leads to hybrid vigour or heterosis. It refers to the superiority of the hybrid over its parents. The changes in the progeny or hybrid can be seen with naked eyes. The main steps include, i.e. selection of parents, selfing of parents, emasculation, bagging, crossing of desired and selected parents and finally seed setting and harvesting.
Question
Golden rice is a transgenic crop of the future with the following improved trait [CBSE AIPMT 2006, 05]
(a) high lysine (essential amino acid] content
(b) insect resistance
(c) high protein content
(d) high vitamin-A content.
Answer/Explanation
Ans. (d)
Generally seeds of rice do not have vitamin-A, but golden rice which is developed through genetic engineering has the high vitamin-A content.
Question
Crop plants grown in monoculture are [CBSE AIPMT 2006]
(a) low in yield
(b) free from intraspecific competition
(c) characterised by poor root system
(d) highly prone to pests
Answer/Explanation
Ans. (d)
The crop plants grown in monoculture are highly prone to pests and thus, it carries the risk of an entire crop being destroyed with the appearance of a single pest species ar disease.
Question
Triticale, the first man-made cereal crop, has been obtained by crossing wheat with [CBSE AIPMT 2006]
(a) rye
(b) pearl millet
(c) sugarcane
(d) barley
Answer/Explanation
Ans. (a)
Triticale is the first man-made cereal crop. It has been obtained by crossing wheat (Triticum sp.| with rye (Secale cerelel).
Question
Three crops that contribute maximum to global food grain production are [CBSE AIPMT 2005]
(a) wheat, rice and maize
(b) wheat, maize and sorghum
(c) rice, maize and sorghum
(d) wheat, rice and barley
Answer/Explanation
Ans. (a)
Wheat, rice and maize belong to familyPoaceae or Gramineae. The main fruit type of these crops is caryopsis in which fruit wall is fused with seed coat. These crops are cultivated in all over the world and are contributed maximum in global food grain production.
Question
The name of Norman Borlaug is associated with [CBSE AIPMT 2005]
(a) Green revolution
(b) Yellow revolution
(c) White revolution
(d) Blue revolution
Answer/Explanation
Ans. (a)
Norman Borlaug is associated with green revolution. The green revolution means an increase in the production of crops particularly cereals, such as wheat, rice and maize.
Question
Why is vivipary an undesirable character for annual crop plants? [CBSE AIPMT 2005]
(a) It reduces the vigour of plant
(b) The seeds cannot be stored under normal conditions for the next season
(c) The seeds exhibit long dormancy
(d) it adversely affects the fertility of the plant
Answer/Explanation
Ans. (b)
Vivipary is the condition when seeds are germinated on the plant. It is an undesirable character for annual crop plants because germinated seeds cannot be stored under normal conditions for the next season.
Question
Which of the following is generally used for induced mutagenesis in crop plants? [CBSE AIPMT 2005]
(a) X-rays
(b) UV (260 nm)
(c) Gamma rays (from cobalt 60)
(d) Alpha particles
Answer/Explanation
Ans. (c)
Cobalt 60 is the synthetic radioactive isotope of cobalt. Gamma rays are produced when an unstable atomic nucleus like cobalt- 60 releases energy to gain stability. Sharbati Sonora and Pusa Lerma are the two important varieties of wheat that are produced by gamma rays treatment of Sonora-64 and Lerma Rojo-64 which are Mexican dwarf wheat varieties.
Question
India’s wheat yield revolution in the 1960 s was possible primarily due to [CBSE AIPMT 2004]
(a) hybrid seeds
(b) increased chlorophyll content
(c) mutations resulting in plant height reduction
(d) quantitative trait mutations
Answer/Explanation
Ans. (c)
India’s wheat yield revolution in 1960s was possible primarily due to the mutations resulting in plant height reduction. In 1963, ICAR introduced many dwarf selections from CIMMYT, including those developed by Norman Borlaug using Norin-10 as the source of dwarfing genes.
Question
Which of the following crops have been brought to India from New world? [CBSE AIPMT 2002]
(a) Cashewnut, potato, rubber
(b) Mango, tea
(c) Tea, rubber, mango
(d) Coffee
Answer/Explanation
Ans. (a)
Cashewnut, potato, rubber are crops that have been brought to India from New World.
Question
51 What is the best $\mathrm{pH}$ of the soil for cultivation of plants? [CBSE AIPMT 2001]
(a) 3.4-5.4
(b) $6.5-7.5$
(c) $4.5-8.5$
(d) 5.5-6.5
Answer/Explanation
Ans. (c)
Most cultivated soils have $\mathrm{pH}$ ranges between 4.5-8.5. However most plants grow best in soils with a neutral or slightly acidic $\mathrm{pH}$.
Question
Before the European invaders which vegetable was/were absent in India? [CBSE AIPMT 2001]
(a) Potato and tomato
(b) Simla mirch and brinjal
(c) Maize and chichinda
(d) Bitter gourd
Answer/Explanation
Ans. (a)
Potato and tomato originated in the New World. They were absent in India previously.
Question
Which statement is correct about centre of origin of plants? [CBSE AIPMT 2001]
(a) More diversity in varieties
(b) Frequency of dominant gene is more
(c) Climatic conditions more favourable
(d) None of the above
Answer/Explanation
Ans. (a)
The centres of origin of plants are more appropriately called the centres of diversity. These are the areas of maximum diversity of these species.
Question
One of the most important reason why wild plants should thrive is that these are good sources of [CBSE AIPMT 2000]
(a) unsaturated edible oils
(b) highly nutritive animals feed
(c) genes for resistance to diseases and pests
(d) rare and highly sought after fruits of medical importance
Answer/Explanation
Ans. (c)
Wild plants have to survive without getting any protection and for this, they evolve various strategies/characters which are exploited by plant breeders like diseases resistance.
Question
The new varieties of plants are produced by [CBSE AIPMT 1999]
(a) selection and hybridisation
(b) selection and introduction
(c) mutation and selection
(d) introduction and mutation
Answer/Explanation
Ans. (a)
The new varieties of plants are produced by selection and hybridisation. In hybridisation, two or more plants of unlike genotype are crossed together to get offsprings with new desirable combinations of characters, as a result of genetic recombination.
Question
The reason why vegetatively reproducing crop plants are best suited for maintaining hybrid vigour is that [CBSE AIPMT 1998]
(a) they can be easily propagated
(b) they have a longer life span
(c) they are more resistant to disease
(d) once a desired hybrid is produced, there are no chances of losing it
Answer/Explanation
Ans. (d)
Vegetative reproduction is the process of multiplication in a small part or portion of the plant body which functions as a propagule and develops into a new individual. Thus, vegetative reproduction does not involve meiosis; hence, recombination and no loss of heterozygosity.
Question
Which one among the following chemicals is used for causing defoliation of forest trees? [CBSE AIPMT 1998]
(a) Amo-1618
(b) Phosphon-D
(c) Malic hydrazide
(d) 2, 4-D
Answer/Explanation
Ans. (d)
2, 4-D (2, 4 dichlorophenoxy acetic acid) is an auxin hormone. It over stimulates the growth activities of the cells of the root due to which roots get destroyed and thus plants finally destroyed. 2, 4-D is used as a defoliant for broad leaves dicots (mainly weeds).
Question
Which plant will loss its economic value, if its fruits are produced by induced parthenocarpy? [CBSE AIPMT 1997]
(a) Grape
(b) Pomegranate
(c) Orange
(d) Banana
Answer/Explanation
Ans. (b)
Testa is the edible part in pomegranate. It is not formed if fruits are produced by parthenocarpy (no seeds will be formed).
Question
Of the world’s top five crops (in terms of annual production) [CBSE AIPMT 1997]
(a) three belong to Poaceae (Gramineae), one to Leguminosae, one to Solanaceae
(b) four belong to Poaceae, one to Leguminosae
(c) four belong to Poaceae, one to Solanaceae
(d) All five belong to Poaceae
Answer/Explanation
Ans. (c)
Top five crops of today are wheat-Triticum aestivum(Poaceae), corn-Zea mays (Poaceae), rice-Oryza sativa (Poaceae), potato-Solanum tuberosum (Solanaceae) and barley-Hordeum vulgare (Poaceae).
Question
Most of our crop plants are [CBSE AIPMT 1994]
(a) autopolyploid in origin
(b) allopolyploid in origin
(c) mixed genotypic in origin
(d) heterozygous in origin
Answer/Explanation
Ans. (a)
Most of our crop plants are autopolyploid in origin.
Question
Haploid plants are preferred over diploids for mutation study because in haploids [CBSE AIPMT 1993]
(a) recessive mutation express immediately
(b) induction of mutations is easier
(c) culturing is easier
(d) dominant mutation express immediately
Answer/Explanation
Ans. (a)
Haploid plants are preferred over diploids for mutation study because of their clear/obvious expression. In nature mutations are generally recessive. In case of a diploid it is difficult to trace out the recessive mutation as its dominant gene is present on other chromosome.
Question
In crop improvement programme, haploids are important because they [CBSE AIPMT 1989]
(a) require one half of nutrients
(b) are helpful in study of meiosis
(c) grow better under adverse conditions
(d) form perfect homozygous
Answer/Explanation
Ans. (d)
Haploids are important in crop improvement programme because they produce a pureline and form perfect homozygous.