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.
How does the embryo get nourishment inside the mother’s body?
What are the advantages of sexual reproduction over asexual reproduction?
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?
How do Mendel’s experiments show that traits may be dominant or recessive?
Explain the nature of the covalent bond using the bond formation in CH3Cl.
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
What processes would you consider essential for maintaining life?
How many structural isomers can you draw for pentane?
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus.
An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.
How can you help in reducing the problem of waste disposal? Give any two methods.
What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
Explain the terms analogous and homologous organs with examples.