NEET SECTION - A [ZOOLOGY - MCQ]

(B)
The neural system provides an organised network of point-to-point connections for a quick coordination. The endocrine system provides chemical integration through hormones.

(C)
Polymorphisms are inheritable from parents to children. DNA fingerprinting is the basis of paternity testing, in case of disputes.

(B)
A single gene can exhibit multiple phenotypic expression. Such a gene is called a pleiotropic gene.

A

(B)
Logistic growth - A population growing in a habitat with limited resources.
Exponential growth - Any species growing exponentially under unlimited resource conditions can reach enormous population densities in a short time.
Expanding age pyramids - The percent individuals of pre-reproductive age is largest followed by reproductive and post reproductive age groups.
Stable age pyramid - The percent individuals of pre-reproductives and reproductive age group are same.

C

(C)
Thyroid hormones play an important role in the regulation of the basal metabolic rate. These hormones also support the process of red blood cell formation. Thyroid hormones control the metabolism of carbohydrates, proteins and fats. Maintenance of water and electrolyte balance is also influenced by thyroid hormones. Thyroid gland also secretes a protein hormone called thyrocalcitonin (TCT) which regulates the blood calcium levels. Melatonin plays a very important role in regulation of system of our body. It maintain sleep wake cycle, body temperature, etc. Thymus helps in development of the immune system.

(B)
Inner parts of cerebral hemispheres and a group of associated deep structures like amygdala, hippocampus etc., form a complex structure called limbic system. Limbic system along with the hypothalamus, it is involved in the regulation of sexual behaviour, expression of emotional reactions (e.g., excitement, pleasure, rage and fear), and motivation.

(C)
Fascicle (Muscle bundles) are formed by many muscle fibres and covered by perimysium and all of it held by epimysium. The thick filaments in A-band are also held together in the middle of this band by a thin fibrous membrane called M-line.

(B)
An excessive loss of fluid from the body can activate osmoreceptors which stimulate the hypothalamus to release ADH. Hence, switch on osmoreceptors. ADH cause an increase in blood pressure. An increase in blood pressure can increase the glomerular blood flow and thereby the GFR.

(A)
Neutrophils are the most abundant cells (60-65%) of the total WBCs and basophils are the least (0.5-1%). Basophils have S-shaped nucleus. Neutrophils, eosinophils and basophils are different types of granulocytes.

(B)
Tetrad formation is seen during zygotene. The final stage of meiotic prophase I is diakinesis. This is marked by terminalisation of chiasmata. Crossing over occurs between non-sister chromatids of the homologous chromosomes.

(A)
Insects like cockroach are uricotelic (excrete uric acid). In addition, the fat body, nephrocytes and urecose glands also help in excretion.

(D)
Mast cells - Areolar tissue serve as support frame work for epithelium.
Inner surface of Bronchiole - Ciliated epithelium bear cilla on their free surface that help to move particles in specific direction.
Blood - Specialised connective tissues.
Tubular parts of nephrons - Cuboidal epithelium help in secretion and absorption.

(C)
Anal styles are paired, short, unjointed structure present only in male and help in sexual dimorphism.

(D)
Phylum Chordata are characterised by the presence of a notochord, a dorsal hollow nerve cord, and paired pharyngeal gill slits. These are triploblastic, coelomate with organ-system level of organisation. Vertebrates have a ventral muscular heart with two, three or four chambers.

(A)
The most unique mammalian characteristic is the presence of mammary gland (milk producing glands), skin possessing hair and presence of external ear or pinnae.

B

(D)
Of these, serum and urine analysis does not fulfil the purpose of early diagnosis of a disease. In early stages of infections, when the disease symptoms are not visible, amplification of pathogenic nucleic acid can be done by PCR, detection of antibodies produced by host against pathogen by ELISA and rDNA technology can serve the purpose of early diagnosis.

(B)
A probe is not a cloning vector rather it is a single-stranded sequence of DNA or RNA used to search for its complementary sequence in a sample genome.

C

(B)
Heroin is a depressant and slows down body functions. Use of marijuana causes increased heartbeat and blood pressure (cardiovascular effects). Cocaine interferes with the transport of dopamine and causes build up of dopamine in the synapses. Morphine is a very effective sedative and painkiller.

B

(B)
The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation. Australian marsupials exhibit this phenomenon and gave varieties of marsupials, e.g., Numbat, Spotted cuscus, Flying phalanger, etc.

(C)
In prokaryotes, such as, E. coli, though they do not have a defined nucleus, the DNA is not scattered throughout the cell. DNA (being negatively charged) is held with some proteins (that have positive charges) in a region termed as 'nucleoid".
The DNA in nucleoid is organised in large loops held by proteins.

(C)
RNA mutates at a faster rate because it is unstable. Therefore, viruses having RNA genome and shorter life span allow them to mutate and evolve at faster rates.

(A)
Down's Syndrome: The cause of this genetic disorder is the presence of an additional copy of the chromosome number 21 (trisomy of 21). This disorder was first described by Langdon Down (1866). The affected individual is short statured with small round head, furrowed tongue and partially open mouth. Palm is broad with characteristic palm crease. Physical, psychomotor and mental development is retarded.

(D)

(C)
Vasectomy is a surgical method of contraception in males. In vasectomy, a small part of the vas deferens is removed or tied up through a small incision on the scrotum. Although sperm production continues in the testes, sperm can no longer reach the exterior. The sperm degenerate and are destroyed by phagocytosis.
Withdrawal or coitus interruptus is one of the natural methods of contraception in which the male partner withdraws his penis from the vagina just before ejaculation so as to avoid insemination.
Cervical caps are barriers that fit snugly over the cervix and block sperm from entering the uterus.
Saheli - the new oral contraceptive for the females contains a non-steroidal preparation, It is a 'once a week' pill with very few side effects and high contraceptive value.

(B)
Amniocentesis involves removal of some of the amniotic foetal cells and dissolved substances. It can be done to detect genetic disorders, chromosomal abnormalities, biochemical defects, etc. It can also reveal a baby's gender Statutory ban on amniocentesis for sex-determination have been done to legally check increasing menace of female foeticides. Its application of sex determination is not one of the strategies of Reproductive and Child Health Care Programme.

(D)
Gonorrhoea is a sexually transmitted disease (STD) caused by the infection with bacterium Neisseria gonorrhoeae. Gonorrhoea can be cured with the proper treatment if detected early. HIV infections, genital herpes and hepatitis-B are incurable STDs.

(C)
First menstrual cycle begins at puberty is called menarche.

B

(C)
Each ejaculatory duct is formed by the union of the duct from the seminal vesicle and the vas deferens. They opens into the prostatic urethra.
Cervical canal (interior of the cervix) along with vagina forms the birth canal.

(B)
Cholecystokinin (CCK), a hormone secreted by I-cells of the upper small intestine. It acts on both pancreas and gall bladder and stimulates the secretion of pancreatic enzymes and bile juice, respectively.
Gastric inhibitory peptide (GIP) is secreted by K-cells of the small intestine. It acts to decrease gastrin and gastrin dependent acid secretion from the parietal cells of the stomach (gastric glands).
Atrial natriuretic factor (ANF) is a peptide hormone secreted by atrial wall of our heart. It decreases blood pressure.
Anti-diuretic hormone (ADH) causes the kidneys to return more water to the blood and thus decrease the urine volume.

(C)
Cartilaginous Joints - Between adjacent vertebrae in vertebral column.
Ball and socket Joint - Between humerus and pectoral girdle.
Fibrous Joint - Between flat skull bones..
Saddle Joint - Between carpal and metacarpal of thumb.

(B)
In majority of nephrons, the loop of Henle is too short and extends only very little into the medulla. Such nephrons are called cortical nephrons. In some of the nephrons, the loop of Henle is very long and runs deep into the medulla. These nephrons are called juxta medullary nephrons.

(B)
In an ECG record, three recognisable waves (P-wave, QRS complex and T-wave) appear with each heartbeat. P-wave - represents atrial depolarisation.
QRS complex - represents ventricular depolarisation.
T-wave - represents ventricular repolarisation.
Q-wave - represents initial phase of ventricular depolarisation i.e., beginning of systole.

(D)
Vital Capacity (VC): The maximum volume of air a person can breathe in after a forced expiration. This includes ERV, TV and IRV or the maximum volume of air a person can breathe out after a forced inspiration.

B

A

(C)
The cytoskeleton in a cell are involved in many functions such as mechanical support, motility, maintenance of the shape of the cell.

(B)
The endomembrane system include endoplasmic reticulum (ER), golgi complex, lysosomes and vacuoles. Since the functions of the mitochondria, chloroplast and peroxisomes are not coordinated with the above components, these are not considered as part of the endomembrane system.