NEET 2021 Zoology Biology Questions with Answers Key Solutions

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Endomembrane system includes Endoplasmic Reticulum, Golgi complex, Lysosomes and Vacuoles

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C peptide present in proinsulin is removed during its maturation. The insulin produced by rDNA technology has only $A$ peptide and $B$ peptide.

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High $pO_{2}$, low $pCO _{2}$, lesser $H ^{+}$concentration and lower temperature are all favourable factors for the formation of oxyhaemoglobin at the alveoli.

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Physalia - Portuguese man-of-war
Limulus (King crab). - Living fossil
Ancylostoma - (Hookworm)
Pinctada - Pearl oyster

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Aspergillus niger - Citric acid
Acetobacter aceti - Acetic acid
Clostridium butylicum - Butyric acid
Lactobacillus - Lactic acid

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Sphincter of Oddi guards the opening of hepatopancreatic duct into duodenum.

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Improving resistance to disease in crop is not an objective of Biofortification of crops.

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The juxtaglomerular cells of kidney produce a peptide hormone called erythropoietin which stimulates erythropoiesis (formation of RBC).

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In Aves (e.g., Neophron), endoskeleton is fully ossified (bony) and the long bones are hollow with air cavities (pneumatic).

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Centrioles duplicate in $S$ phase of cell cycle

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The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units $(DU)$.

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House fly belongs to family Muscidae

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Metagenesis is exhibited by cnidarians (not helminths). Comb plates of ctenophores help in locomotion (not digestion).

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Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immunosorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis.

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One of the glycoproteins in the zona pellucida, called ZP3, acts as a sperm receptor.

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Myasthenia gravis is an autoimmune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.

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$LNG\, 20$ is a hormone-releasing intrauterine device. It releases $20$ micrograms of levonorgestrel (synthetic progestogen) per day. Progestasert is also a hormonereleasing IUD. $Cu T , Cu 7$ and Multiload 375 are hormone-releasing IUDs.

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Vaults - Entry of sperms through cervix is blocked
IUD's - Phagocytosis of sperms within the uterus
Vasectomy - Removal of vas deferens
Tubectomy - Removal of fallopian tube

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Metamerism - Annelida
Canal system - Porifera
Comb plates - Ctenophora
Cnidoblasts - Coelenterata

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During mitotic cell cycle if the chromosome number in $G _{1}$ phase is $8$ , it remains same till Metaphase. Hence, even after $S$ phase same chromosome number $8$ is maintained in the cell of fruit fly.

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During $PCR$ process, if high temperature is not maintained, the initial step of the process known as denaturation of DNA is not done.

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Thymine $-30 \%$, Guanine $-20 \%$, Cytosine $-20 \%$ (Chargaffs nitrogen base pairing rule which states that amount of Adenine is equal to Thymine and Guanine is equal to Cytosine.

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The enzyme thrombin converts inactive fibrinogens in the plasma into fibrins

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Succus entericus is also called intestinal juice. The secretions of the brush border cells of the mucosa along with the secretions of the goblet cells constitute the intestinal juice.

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Ricin is toxin but not drug

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During Diakinesis of meiotic Prophase $I$, the distinctive feature of this stage, terminalisation of chiasmata is seen.

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Persons with 'AB' group can accept blood from persons with $A B$ as well as the other groups of Blood because they do not have anti $A$ and anti $B$ antibodies in their blood plasma.

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Palindromic Nucleotide sequence is specific recognition sequence identified by endonucleases to cut the DNA strands at the specific positions.

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A ring of $6-8$ blind tubules called hepatic or gastric caeca is present at the junction of foregut and midgut, which secrete digestive juice.

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$siRNA$ (smaller interference RNA) is involved in preventing the translation of $mRNA$ to form protein. It is associated with pest resistance in plants by $RNA$ interference.

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DNA dependent RNA polymerase of prokaryotes has the ability to initiate, elongate and terminate the process of transcription.

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In the alveolar air, the partial pressures of oxygen $\left( pO _{2}\right)$ is $104\, mm\,Hg$ and that of carbon dioxide $\left( pCO _{2}\right)$ is $40\, mm\,Hg$.

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Cow is administered hormone having LH like activity for super ovulation

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Relaxin is produced first by the corpus luteum of the ovary and later by the placenta. It helps in parturition as it increases the flexibility of the pubic symphysis and helps dilate the uterine cervix.

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During muscle contraction, the cross bridges pull the thin filaments towards the center of A band. The $Z$ line attached to the actins are also pulled inwards thereby causing a shortening of the sarcomere. The $I$ bands get reduced, whereas the 'A' bands retain the length. Myosin head acts as ATPase.

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Lecithin is a phospholipid. Glycerol is trihydroxy propane. Unsaturated fatty acids have double bonds in R group at one or more regions.

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Histones are basic proteins. Hence, they are alkaline or basic because of abundance of basic amino acids Lysine and Arginine.

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Adaptive Radiation - Darwin Finches
Convergent evolution -Wings of Butterfly and Bird
Divergent evolution Bone of forelimbs in Man and Whale
Evolution by anthropogenic action-Selection of resistant varieties due to excessive use of herbicides and pesticides

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Tight junctions help to stop substances from leaking across a tissue. Gap junctions facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells, for rapid transfer of ions, small molecules and sometimes big molecules.

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Anterior end consists of the mouth and the prostomium, a lobe which serves as a covering for the mouth and as a wedge to force open cracks in the soil into which the earthworm may crawl. The prostomium is sensory in function. The first body segment is called the peristomium (buccal segment) which contains the mouth.

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Adenosine deaminase (ADA) is crucial for the immune system to function. Its deficiency causes severe combined immunodeficiency.

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AUG codes for only methionine but not tryptophan. ( A given codon codes for only one amino acid but not more than one amino acids.). AAG and AAA are the two codons for the amino acid Lysine.

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A person goes to high altitude and experiences altitude sickness with symptoms like breathing difficulty and heart palpitations because in the low atmospheric pressure of high altitudes, the body does not get enough oxygen.

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Allen's Rule - Polar seal
Physiological adaptation - Kangaroo rat
Behavioural adaptation - Desert lizard
Biochemical adaptation - Marine fish at depth

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Filariasis - Wuchereria bancrofti
Amoebiasis - Entamoeba histolytica
Pneumonia - Haemophilus influenzae
Ringworm - Trichophyton

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Release of Prolactin is not an important component of initiation of parturition in humans. Towards the end of pregnancy, the increasing ratio of estrogen to progesterone promotes uterine contractions. Progesterone no longer inhibits them. High levels of estrogens increase the number oxytocin receptors and gap junctions in the myometrium. Prostaglandins induce the softening of uterine cervix and enhance uterine contractile strength.

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Scapula - Triangular flat bone
Cranium - Fibrous joint
Sternum - Flat bone
Vertebral column - Cartilaginous joint