How does the embryo get nourishment inside the mother’s body?
Embryo gets nourishment inside the mother’s body through the placenta. Placenta is an organ which forms in uterus during the pregnancy and is less than 1kg in weight. It helps to bring the foetus and the maternal blood close enough for the exchange of oxygen and nutrition and it also removes the waste product from the baby’s blood. And, it also has the umbilical cord (naval string) which is attached near the centre of placenta to the foetus.
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 reproduction help in providing stability to populations of species?
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?
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Write a balanced chemical equation with state symbols for the following reactions:
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?
By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic?
Ga Ge As Se Be
Define the unit of current.
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
What are the limitations of extracting energy from—
(a) the wind? (b) waves? (c) tides?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?