How is the process of pollination different from fertilisation?
Pollination:- Transfer of pollen grain from the anther (male part of the flower) of stamen to the stigma (female part of the flower) of carpel is known as pollination. It is of two types:-
Self pollination:- It involves the transfer of pollen grains from the anther to the stigma of the same flower or genetically similar flower.
Cross pollination:- It involves the transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant.
Transfer of pollen grains can be occur through many agents like anemophily (wind pollination), hydrophily (water pollination), entomophily (insect pollination), ornithophily (pollination by birds) and chiropterophily (bat pollination).
Fertilisation:- Fusion of haploid male gamete (spermatozoan) and a haploid female gamete (ovum) and they together forms a diploid cell, i.e, zygote is known as fertilisation.
Why is variation beneficial to the species but not necessarily for the individual?
Draw a labelled diagram of the longitudinal section of a flower.
What are the functions performed by the testis in human beings?
Why does menstruation occur?
How will an organism be benefited if it reproduces through spores?
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.
What are the advantages of sexual reproduction over asexual reproduction?
How does the embryo get nourishment inside the mother’s body?
What is the importance of DNA copying in reproduction?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.
An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.
Choose the correct option.
The magnetic field inside a long straight solenoid-carrying current
(a) is zero.
(b) decreases as we move towards its end.
(c) increases as we move towards its end.
(d) is the same at all points.
The change in focal length of an eye lens is caused by the action of the
(a) pupil. (b) retina.
(c) ciliary muscles. (d) iris.
Balance the following chemical equations.
(a) HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
(b) NaOH + H2SO4 → Na2SO4 + H2O
(c) NaCl + AgNO3 → AgCl + NaNO3
(d) BaCl2 + H2SO4 → BaSO4 + HCl
A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards south (b) towards east
(c) downward (d) upward
Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?
Which sources produce alternating current?
How does chemical coordination occur in plants?
Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 Ω resistor. What would be the readings in the ammeter and the voltmeter?