When synapsis is complete all along the chromosome, the cell is said to have entered a stage called
zygotene
pachytene
diplotene
diakinesis
B.
pachytene
Prophase I consists of 5 stages:
(i) Leptotene- Chromosomes become gradually visible.
(ii) Zygotene- Synapsis, pairing of homlogous chromosomes takes place. It results in the formation of bivalents. Also, formation of special proteinaceous structure called synaptonemal complex occur.
(iii) Pachytene- Cells that eneterd this phase results in spiralling, shortening and thickening of the bivalents.
(iv) Diplotene- Dissolution of synaptonemal complex takes place. Also, recombined homologous chromosomes of the bivalents seperate.
(v) Diakinesis- Terminalisation of chiasmata occur in this phase.
Many cells function properly and divide mitotically even though they do not have
plasma membrane
cytoskeleton
mitochondria
plastids
Which one of the following four secretions is correctly matched with its source, target and nature of action?
| Secretion | Source | Target | Action |
| Gastrin | Stomach lining | Oxyntic cells | Production of HCl |
| Inhibin | Sertoli cells | Hypothalamus | Inhibition of secretion of gonadotropin releasing hormone |
| Enterokinase | Duodenum | Gall bladder | Release of bile juice |
| Atrial Natiuretic Factor (ANF) | Sinu atrial node (SAN) M- cells of Atria | Juxta- glomerular apparatus (JGA) | Inhibition of release of renin |
Based on cellular mechanisms there are two major types of regeneration found in the animals. Which one of the following is the correct example of the type mentioned?
Morphallaxis - Regeneration of two transversely cut equal pieces of a Hydra into two small Hydras
Epimorphosis - Replacement of old and dead erythrocytes by the new ones
Morphallaxis - Healing up of a wound in the skin
Epimorphosis - Regeneration of crushed and filtered out pieces of a Planaria into as many new Planarians
Which one of the following statements pertaining to plant structure is correct?
Cork lacks stomata, but lenticels carry out transpiration.
Passage cells help in transfer of food from cortex to phloem
Sieve tube elements possess cytoplasm but no nuclei.
The shoot apical meristem has a quiescent centre
Which one of the following statements is correct with respect to salt water balance inside the body of living organisms?
when water is not available camels do not produce urine but store urea in tissues.
Salmon fish excretes lot of stored salt through gill membrane when in fresh water
Paramecium discharges concentrated salt solution by contractile vacuoles
The body fluids of fresh water animals are generally hypotonic to surrounding water
Which one of the following four glands is correctly matched with the accompanying description ?
Thyroid - hyperactivity in young children causes cretinism
Thymus - starts undergoing atrophy after puberty
Parathyroid - secretes parathormone which promotes movement of calcium ions from blood into bones during calcification
Pancreas - Delta cells of the Islets of Langerhans secrete a hormone which stimulates glycolysis in liver
Formation of non-functional methaemoglobin causes blue-baby syndrome. This is due to
excess of arsenic concentration in drinking water
excess of nitrates in drinking water
deficiency of iron in food
increased methane content in the atmosphere
The family containing mustard and its main characters are
Brassicaceae - Tetramerous flowers, six stamens, bicarpellary gynoecium, siliqua type fruit
Brassicaceae - Pentamerous flowers, many stamens, pentacarpellary gynoecium, capsule type fruit
Solanaceae - Pentamerous flowers, five stamens, bicarpellary gynoecium, berry type fruit
Poaceae - Trimerous flowers, three stamens, monocarpellary gynoecium, caryopsis type of fruit.
Two of the body parts which do not appear in MRI may be
molar teeth and eye lens
scapula and canines
ligaments and ribs
tendons and premolars
