Medical Entrance Exams NEET practice set-4 Hints
hints and solutions
1. Cajanus cajan (Arhar) is a legume having root nodule that contains fixing symbiotic bacterium Rhizobium leguminosarum. Hence this plant can grow in nitrogen-deficient soil.
2. In Cycas (a gymnosperm), pollen tube is formed. However, fertilization is siphonogamy followed by zooidiogamy, water is not essential as ciliated gametes swim within pollen tube.
3. In the genotype AABbCC, The number of allele (n) = number of heterozygote = 1Thus, phenotypic ratio = (3 : 1) = (3 : 1) = 3 :1.
4. The plant, that all body is root only, is Podostemon. Reproduction and assimilation are performed by root.
5. Loosely arranged thick-walled, suberised cells of lenticel are called complementary cells.
6. Alcohol treatment causes loss of selective permeability of the membrane and hence there will be no change when this alcohol treated cell is placed in a hypertonic solution of sucrose.
7. Obligate symbiotic relationship occurs between Yucca flowers and a moth, Aedicula.
8. According to Cholodny-Went theory, IAA is responsible for phototropism and geotropism.
9. DDT is non-degradable and hence biologically magnified, i.e., its concentration goes on increasing with each and every trophic level along the food chain.
10. Insulin is the first hormone produced by culturing E. coli in which insulin-producing genes have been transferred from human beings. This hormone called Humulin was developed by E li Lily.
11. Interferons are antiviral agents controlling viral infection causing cancer in which RSV (Rous sarcoma virus) is associated. Alliac Issacs and Lindeman (1957) gave the term interferons to the chemical substance responsible for viral interferons, Holleman and A. Tyndall isolated interferon from hen’s egg infected with influenza virus.
12. A segment of DNA responsible for the appearance and inheritance of a character is called a gene. A DNA is a polymer of several thousand pairs of nucleotides. Thus, genes are chemically polynucleotides.
13. Most important foods are derived from grains (caryopsis fruit) of cereals (family Poaceae).
14. Axillary or lateral bud is a cluster of dormant meristem cells left behind by the apical meristem as the stem grows. The terminal bud induces the apical meristem and several leaf primordia produced by meristems.
15. In sweet pea (Lathyrus odoratus), C and P are complementary factors, i.e., flower colour is produced when both these dominants (C and P) are present together.
16. A proteolytic enzyme, which digests protein, is secreted by glands found in insectivorous plants like Drosera.
17. Two nuclei are involved in syngamy and three nuclei in triple fusion.
18. Leaves are the most sensitive parts to air pollution, especially pollution.
19. Marine algae flourished well during the Ordovician period of the Paleozoic era.
20. Cosmids are the plasmids that contain lambda phase ‘cos’ site and these are used to clone long segments of DNA.
21. No reserve food materials like fats, proteins and sugars are present in meristematic cells.
22. At incipient plasmolysis, the cell wall exerts no pressure on the cell contents and thus wall pressure or pressure potential () is zero and thus water potential is equal to solute potential () as =.
23. The atomic ovule is found in parasitic angiosperms.
24. Delay in senescence by cytokinins is called Richmond – Lang effect.
25. According to Lindemann’s 10% law of energy transfer, only 10% of chemical energy within producer tissue becomes chemical energy in herbivore tissue.
26. Competition is a type of cold war in which both the organisms are harmed. Competition is for basic necessities of life. It may be interspecific or intraspecific. The latter is more severe because organisms of same species have similar basic requirements.
27. All growth regulators are not natural. Some of them are synthetic. Growth regulators are of two type, growth promoters and growth inhibitors.
28. Ovule having two integuments, outer and inner are called bitegmic ovule. It is more common in angiosperms and has been found in 208 families. It is found in Polypetalae of dicots and the members of monocots. In Gamopetalous of dicots, ovule is unitegmic.
29. The loss of water in the form of droplets from the tip and margins of leaves is called guttation. In general, guttation occurs when transpiration rate is very low as compared to the rate of water absorption. Due to this, root pressure is developed and water is pushed out through specialized pore at vein endings called hydathodes. So guttation is not due to the activity of hydathodes but due to root pressure.
Water lost in guttation per plant per night is generally up to 100ml. but in Colocasia antiquorum, it is maximum and is 200ml/plant/night.
30. Red algae have phycocyanin and phycoerythrin. These pigments can utilize wavelengths of 480-520nm (blue-green region of the spectrum). This enables red algae to grow at greater depths than other plants (up to 300ft. below water).
Reserve food products are polysaccharides, i.e., floridean starch.
31. The six-unit is called gamete. It has a haploid number of chromosomes. Homozygous individuals have both factors being identical, e.g., TT, tt, while heterozygous individuals have different factors, e.g., Tt. Albinism is caused by a recessive autosomal gene (aa). Albinos are colourless individuals.
32. Resin or turpentine is obtained from Pinus sp. Sago grain is obtained from Cycas revoluta (sago palm). However, commercially sago is obtained from actual palm Metroxylon rumphii. Amber is obtained from Ephedra. Canada balsam is obtained from Abies balsamea.
33. A corymb is a type of racemose inflorescence in which axis is shortened and having pedicellate flowers lying at the same plane, e.g., candytuft (Iberis amara), Shepherd’s purse (Capsella bursa-pastoris). The spadix is a spike having a thick and fleshy axis, e.g. banana (Musa). Capitulum or racemose head is an advanced type of racemose inflorescence, e.g. Asteraceae. Cyathium is a cup-shaped special type of inflorescence, e.g. Euphorbia.
34. Collateral and the open vascular bundle is the characteristic of dicot stem. The radial vascular bundle is found in the root. By collateral vascular bundles are found in the members of Cucurbitaceae, Solanaceae and Myrtaceae. The concentric vascular bundle is found in ferns.
35. Warming (1909) was the first ecologist who recognised the importance of soil as an ecological factor and he divided plants into five different types on the basis of soil.
(i) Halophytes – Plants growing in salty or saline soil.
(ii) Oxylophytes – Plants growing in sandy soil
(iii) Psammophytes – Plants growing in sandy soil
(iv) Chasmophytes – Plants growing in rock crevices
(v) Lithophytes – Plants growing on rocks.
36. A sulphur containing amino acid serves as a precursor of ethylene in all higher plant tissues.
37. It is the smallest parasite angiosperm growing on the stem of Pinus excelsa in Kumaon hills. In this plant, anther is horse-shoe shaped, monothecous and monosporangiate.
38. It is also called wreath or ring or halo anatomy. Here vascular bundles are surrounded by the sheath of large parenchyma cells called bundle sheath, which is surrounded by mesophyll cells.
39. Rhizopus is a saprophytic fungus growing on the dead organic matter.
46. They bear small pores called lenticels (Pneumathodes) near their tips.
47. It is a narrow strip of tissue (Parenchyma ous and sclerenchymatous) that lies between xylem and phloem of the root.
48. It is the phenomenon of conversion of ammonium compound to nitrate.
49. It is the study of genomes and genes in relation to DNA sequences.
50. The entire sequence of development stages of biotic succession from pioneer to a climax community is known as sere.