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?
What is the importance of DNA copying in reproduction?
How does reproduction help in providing stability to populations of species?
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 does our body respond when adrenaline is secreted into the blood?
How do auxins promote the growth of a tendril around a support?
How does chemical coordination take place in animals?
Draw the structure of a neuron and explain its function.
Which signals will get disrupted in case of a spinal cord injury?
Which part of the brain maintains posture and equilibrium of the body?
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.
The xylem in plants are responsible for
(a) transport of water. (c) transport of amino acids.
(b) transport of food. (d) transport of oxygen.
Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
How do Mendel’s experiments show that traits are inherited independently?