A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is :
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Solution
Commensalism is an interaction where one species is benefitted and other is neither benefitted nor harmed.
Assume 2n =12 in a hypothetical species. In gametogenesis, the number of chromosomes in a spermatid would be __________ and in a first polar body would be __________
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Solution
Haploid sex cells contain half as many chromosomes as diploid somatic cells.
Water potential is equal to
Which of the following meristems is responsible for extrastelar secondary growth in dicotyledonous stem?
Drosophila flies with XXY genotype are females but in case of humans, such individuals are abnormal males (Klinefelter’s syndrome). This indicates that
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Solution
In human the Y chromosome bears the androgenic factor or the male determining factor. Whereas in Drosophila the ratio of sex chromosomes to autosomes is the factor determining sex of the individual.
“Foolish seedling’’ disease of rice led to the discovery of
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Solution
The effect of gibberellins had been known in Japan since early 1800 where certain rice plants were found to suffer from bakane or bakanae (foolish seedling) disease. Such rice plants were thin, pale green, spindle-shaped, longer by 50% than the healthy plants, and were sterile.
Amniocentesis is the with draw of amniotic fluid in –
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Solution
Amniotic fluid is secreted by amnion of foetus during pregnancy.
How many base pairs (bp) are found in the haploid genome of humans?
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Solution
The number of base pairs (bp) found in the haploid genome of humans is 2.9 × 109.
One of the following is a very unique feature of the mammalian body –
In photosynthesis, hydrogen is transferred from the light reactions to dark reactions by–
Which of the following hormones is not a secretion product of human placenta ?
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Solution
Human chorionic gonadotropin is released by Anophoblast cells of the placenta. Estrogen and progesterone are also released by placental cells to maintain pregnancy. Prolactin is secreted from anterior lobe of pituitary. Placenta secretes Human Placental Lactogenic Factor which prepare mammary glands to secrete milk.
Glycogenesis is the result of the hormone of
Nerve fibres conduct impulses in
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Solution
If a nerve impulse was initiated somewhere in the middle of a nerve fibre, it would proceed to both ends. However,in the synapse, the progagation is strictly one-way from the axon to the dendrite and never the reverse.
Most of the digestion in cockroach occurs in
Vasopressin stimulates reabsorption of water and reduction of urine secretion. Hence vasopressin is otherwise called
The study of formation, growth and development of new individual from an egg is called
Water potential of pure water and its solution are
Select the two correct statements out of the four (a–d) given below about lacoperon.
1. Glucose or galactose may bind with the repressor and inactivate it.
2. In the absence of lactose the repressor binds with the operator region.
3. The z-gene codes for permease.
4. This was elucidated by Francois Jacob and Jacque Monod.
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Solution
Jacob and Monod proposed the lac operon of E. coli.The lac operon contains a promoter, an operator, and three structural genes called Z, Y,and A, coding for the enzyme, β galactosidase, permease and transacetylase respectively. The lac regulator gene, designated as i gene,codes for repressor. In the absence of the inducer, the repressor binds to the lac operator, preventing RNA polymerase from binding to the promoter and thus transcribing the structural gene.
Epithelial tissue performs the following functions
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Solution
Epithelial tissues have a widespread distribution throughout the body and serve several important functions such as protection, sensation and absorption.
A plant differs from an animal mainly in: