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NEET 2020 Biology Questions with Answers Key Solutions
Solution:
Natality, Mortality and sex ratio are attributes of a population. Species interaction can be inter or intraspecific, where population forms the part of the species confined by geographical or other environmental barriers.
Solution:
Maximum growth takes place during exponential or log phase.
Solution:
The fibrous roots originate from the base of the stem. The primary root originates at the germination stage from the radicle of the seed.
Solution:
• Typhoid — Salmonella
• Pneumonia — Haemophilus
• Filariasis — Wuchereria
• Malaria — Plasmodium
Solution:
ZIFT and IUT are the techniques in which embryos are transfer red to assist those females who cannot conceive
Solution:
When $I^A$ and $I^B$ are present together, they both express their own type of sugars.
Solution:
• Polymerases— Polymerization of nucleotides
• Nucleases — Digestion of nucleic acid
• Exonucleases— Remove nucleotides from the end of
DNA
Solution:
• Haemophilia—X linked recessive disorder
• Phenylketonuria—Autosomal recessive disorder
• Sickle cell anaemia—Autosomal recessive trait
• Thalassemia—Autosomal recessive trait
Solution:
• Gregarious, polyphagous pest— Locusta
• Adult with radial symmetry and larva with bilateral symmetry —Asterias
• Book lungs—Scorpion
• Bioluminescence—Ctenoplana
Solution:
The infectious stage of Plasmodium that enters the human body is sporozoites.
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Q11. identify the substances having glycosidic bond and peptide bond, respectively in their structure
Solution:
Glycosidic bond is present in carbohydrates (like inulin) and peptide bond is present in proteins (like insulin).
Solution:
(a) Pollen grains inside the anther
(d) Embryo sac inside the ovule
Q13. The product(s) of reaction catalyzed by nitrogenase in root nodules of leguminous plants is/are :
Solution:
Nitrogenase enzyme catalyses the nitrogen fixation in root nodules of leguminous plants. The reaction is as follows:
$N_2 + 8e^- + 8H^+ + 16ATP \rightarrow $
$2NH_3 + H_2 + 16ADP + 16Pi$
So, products of nitrogen fixation are both ammonia and hydrogen
Solution:
DNA synthesis takes place in S-phase
Solution:
Cuboidal epithelium with brush border of microvilli is found in proximal convoluted tubule (PCT) of nephron.
Solution:
Inclusion bodies are not involved in ingestion of food.
Q17. Which is the important site of formation of glycoproteins and glycolipids in eukaryotic cells ?
Solution:
The important site of formation of glycoprotein and glycolipids in eukaryotic cells is Golgi bodies.
Solution:
In agarose gel electrophoresis, separated DNA fragments can be visualised with the help of ethidium bromide in UV radiation.
Solution:
Lower hydrogen ion concentration in alveoli favours the formation of oxyhaemoglobin.
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Solution:
The specific palindromic sequence which is recognized by EcoRI is
5' - GAATTC - 3'
3' - CTTAAG - 5'
Solution:
Restriction endonucleases make cuts at specific positions within the DNA. They function by inspecting the length of a DNA sequence. Restriction endonuclease binds to the DNA and cuts the two strands of the double helix at specific points in their sugar-phosphate backbones. They are used in genetic engineering to form recombinant molecules of DNA. DNA ligases join the DNA fragments
Solution:
Activated sludge is put into anaerobic sludge digester for further sewage treatment.
Solution:
Events that occur during inspiration are
(a) Contraction of diaphragm
(b) Contraction of external intercostal muscles
(c) Pulmonary volume increases
(d) Intra pulmonary pressure decreases
Solution:
In urochordata, notochord is present only in larval tail. In adults, notochord is absent.
• Chordata is divided into $3$ subphyla—Urochordata, Cephalochordata and Vertebrata.
Solution:
(a) Bacillus thuringiensis — Cry proteins
(b) Thermus aquaticus — DNA polymerase
(c) Agrobacterium tumefaciens —Cloning vector
(d) Salmonella typhimurium — Construction of first rDNA molecule
Solution:
• Iron — Required for chlorophyll biosynthesis
• Zinc — LAA biosynthesis
• Boron — Pollen germination
• Manganese—Photolysis of water
Solution:
Sapwood is the peripheral part of the secondary xylem and is lighter in colour.
Solution:
• Inhibitor of catalytic activity —Malonate
• Possess peptide bonds — Collagen
• Cell wall material in fungi —Chitin
• Secondary metabolite — Ricin
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Solution:
Meiotic division of the secondary oocyte is completed at the time of fusion of a sperm with an ovum.
Solution:
According to Robert May, the global species diversity is about 7 million.
Solution:
The first phase of translation is aminoacylation of tRNA or charging of tRNA.
Solution:
Highest species diversity occurs in Amazon Rainforest.
Solution:
The functional insulin has A and B chains linked together by disulfide bonds.
Solution:
• 6-15 pairs of gill slits — Cyclostomes
• Heterocercal caudal fin — Chondrichthyes
• Air bladder — Osteichthyes
• Poison sting — Trygon
Q38. From his experiments. S.L.Miller produced amino acids by mixing the following in a closed flask
Solution:
Miller produced amino acids by mixing $CH_4, NH_3, H_2$ and water vapour at $800^{\circ}C$.
Solution:
Embryological support for evolution was proposed by Ernst Haeckel.
• Embryological support for evolution was disapproved by Karl Ernst von Baer.
Solution:
Loss of water in liquid form from the tip of grass blades in night and in early morning is called guttation, which occurs due to positive root pressure.
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Q41. Secondary metabolites such as nicotine, strychnine and caffeine are produced by plants for their
Solution:
Nicotine, strychnine and caffeine are produced by plants for their defence action against grazers and browsers.
Solution:
The oxygenation of RuBisCo enzyme during photorespiration leads to the formation of 1 molecule of 3-C compound PGA and 1 molecule of 2-C compound Phosphoglycolate. So, the correct answer is '1 molecule of 3-C compound and 1 molecule of 2-C compound'.
Solution:
Bt cotton variety is resistant to insect pests.
Solution:
Examples of evolution due to anthropogenic action (due to human activities) are as follows:
(a) Herbicide resistant weeds
(b) Drug resistant eukaryotes
(c) Pesticide resistant insects
(d) Creation of new breeds of drugs
Solution:
Active immunity is slow and takes time to give its full effective response.
Q46. By which method was a new breed 'Hisardale' of sheep formed by using Bikaneri ewes and Marino rams ?
Solution:
Hisardale is a new breed of sheep developed by cross breeding technique.
Solution:
• Ileum opens into caecum.
• Serosa is the outermost layer of alimentary canal.
• Vermiform appendix arises from caecum.
Solution:
(a) Clostridium butylicum — Butyric acid
(b) Trichoderma polysporum — Cyclosporin-A
(c) Monascus purpureus — Blood cholesterol lowering agent
(d) Aspergillus niger — Citric acid
Solution:
Ketonuria (presence of ketone bodies) and glycosuria (presence of glucose) conditions in urine are indicative of diabetes mellitus.
Solution:
Floridean starch has structure similar to amylopectin and glycogen (being branched).
Solution:
Sexually transmitted diseases are gonorrhoea, syphilis, genital herpes, genital warts, AIDS, trichomoniasis, chlamydiasis, hepatitis-B, etc.
Solution:
• Zygotene—Synapsis
• Pachytene — Crossing over
• Diplotene — Chiasmata
• Diakinesis — Terminalization
Solution:
Chlorella and Spirulina are unicellular green algae, which are commercially very important. Anabaena is Cyanobacteria, Laminaria, Sargassum, Gelidium, Gracilaria are multicellular algae. Volvox is unicellular colonial algae.
Solution:
Ovulation occurs when the level of hormones is as follows:
(a) High concentration of estrogens
(b) Low concentration of progesterone
(c) High concentration of LH
(d) High concentration of FSH
Solution:
• Bt cotton — Bacillus thuringiensis
• Adenosine deaminase deficiency—Gene therapy
• RNAi—Cellular defence
• PCR—Detection of HTV infection
Solution:
Montreal protocol was signed in 1987 for control of emission of ozone depleting substances.
Solution:
Viroids have free RNA without protein coat (capsid).
Solution:
Plum, peach and rose flowers are perigynous and ovary is half inferior.
Solution:
The enzyme enterokinase helps in conversion of inactive trypsinogen into active trypsin.
Solution:
• Fourth trophic level — Vulture
• Second trophic level — Rabbit
• First trophic level—Grass
• Third trophic level — Crow
Solution:
Mendel selected 14 true breeding pea plant varieties.
Solution:
• Organ of Corti—Located on the basilar membrane
• Cochlea—Coiled part of the labyrinth
• Eustachian tube—Connects middle ear and pharynx
• Stapes—Attached to the oval window
Solution:
In water hyacinth, that is, Eichhornia the flowers are purple in color, attractive and borne in a spike to facilitate pollination by insects. Water lilies, Nymphea species have conspicuous attractive flowers to facilitate insect pollination while some species produce a large number of pollen grains to aid anemophily or wind pollination. So, the correct answer is 'Insects or wind'.
Solution:
Gibberellin upon spraying on sugarcane crop, increases the length of stem, thus increasing the yield of sugarcane crop by 20 tonnes per acre.
Solution:
In light reaction, plastoquinone facilitates transfer of electrons from PS-II to $Cyt b_6f$ complex.
Solution:
Gibberellic acid breaks seed dormancy by activating enzyme α - amylase. While abscisic acid and phenolic acid induce seed dormancy. So, the correct answer is 'Gibberellic acid'.
Solution:
DNA dependent RNA polymerase somehow also facilitates opening of helix and continues elongation. It uses nucleoside triphosphates as substrate and polymerises in a template depended fashion following the rule of complementarity.
DNA helicase unwind the DNA helix and unzips the the two strands.
DNA polymerase adds complementary deoxyribo nucleotides towards the 3' end of primer.
DNA ligase facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond.
Solution:
• Less water reabsorption takes place due to under secretion of ADH.
• Atrial natriuretic factor (ANF) causes vasodilation.
• Diuresis is prevented by increase in secretion of renin by JG cells.
Solution:
GPP- R=NPP
• GPP is always more than NPP
Solution:
• Placenta — Human Chorionic Gonadotropin (hCG)
• Zona pellucida — Layer of the ovum
• Bulbo urethral glands — Lubrication of the penis
• Leydig cells — Androgens
Solution:
Strobili or cones are the dense and compact structures present on non-flowering plants. They contain sporangia and perform function of protecting spores from wild animals and harsh conditions of environment. In Equisetum, the strobili are present at the terminal position on stem. Equisetum are also known as horsetails and come under the category of ferns.
Solution:
Some dividing cells at the end of mitotic phase exits the cell cycle and enter into a vegetative inactive stage, also called quiescent phase. Heart cells enter this phase. The $G _0$ phase is occurs during $G _1$ phase.
Solution:
Flippers of penguins and dolphins are examples of analogous organs or convergent evolution.
Solution:
Length of DNA = Number of base pairs $\times 0.34\, nm$
$= 6.6 \times 10^9 \times 0.34 \,nm$
$= 6.6 \times 10^9 \times 0.34 \times 10^{-9} m$
$= 2.2 \,m$
Solution:
• P-wave: Depolarisation of atria
• QRS-complex: Depolarisation of ventricles
• T-wave: Repolarisation of ventricles
Solution:
• Eosinophils — Release histaminase destructive enzymes
• Basophils — Release granules containing histamine
• Neutrophils—Phagocytosis
• Lymphocytes — Immune response
Solution:
Adenine pairs with thymine through two H-bonds.
Solution:
The sequence that controls the copy number of the linked DNA in the vector is called Ori (Origin of replication)
Solution:
• Tyrosine— Aromatic amino acid
• Glutamic Acid— Acidic amino acid
• Lysine — Basic amino acid
• Valine — Neutral amino acid
Solution:
• Pituitary gland—Diabetes insipidus
• Thyroid gland—Grave’s disease
• Adrenal gland—Addison’s disease
• Pancreas—Diabetes mellitus
Solution:
• Glucagon is associated with hyperglycemia.
• Insulin acts on adipocytes and hepatocytes.
• Insulin is associated with hypoglycemia.
Solution:
Most abundant protein in animals is collagen.
Solution:
• Chromosomal theory of inheritance was given by Sutton and Boveri.
• The experimental verification of chromosomal theory of inheritance was given by T.H. Morgan.
Solution:
• Floating Ribs — Do not connect with the sternum
• Acromion—Clavicle
• Scapula — Located between second and seventh ribs
• Glenoid cavity —Head of the Humerus
Solution:
In one turn of citric acid cycle (Kreb’s cycle), substrate level phosphorylation occurs at one step when succinyl CoA is converted into succinic acid.
Solution:
Dissolution of the synaptonemal complex occurs during diplotene stage of prophase I.
Solution:
• Ctenophora — Radial symmetry
• Platyhelminthes — Bilateral symmetry— Acoelomate
• Aschelminthes — Bilateral symmetry — Pseudocelomate
• Annelida — Bilateral symmetry — Schizocoelomate (True coelomate)
Solution:
The body of the ovule fuses within funicle in the region called hilum
Solution:
Goblet cells of alimentary canal secrete mucus and are modified from columnar epithelial cells.
Solution:
Snow blindness or photokeratitis is the inflammation of the cornea due to excessive exposure to UV-B radiation. So, the correct answer is 'Inflammation of cornea due to high dose of UV-B radiation'
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