Biology
The diagram given below is that of a developing human foetus. Study the diagram and then answer the questions that follow:
(i) Label the parts numbered 1 to 3 in the diagram.
(ii) Mention any two functions of the part labelled 2 in the diagram.
(iii) Explain the significance of the part numbered 3 in the diagram.
(iv) Define the term 'Gestation'. What is the normal gestational period of the developing human embryo?
(v) Mention the sex chromosomes in a male and female embryo.
Answer
(i) The parts numbered 1 to 3 in the diagram are:
- 1 → Umbilical cord
- 2 → Placenta
- 3 → Amniotic fluid
(ii) Two functions of Placenta are:
- Acts as a barrier and prevents germs from entering foetal blood.
- Secretes Oestrogen and Progesterone.
(iii) Protects the embryo from physical damage by jerks or mechanical shocks, keeps an even pressure all around the embryo and allows the foetus some restricted movement.
(iv) The full term of the development of the embryo in the uterus is called gestation. In humans, it lasts for about 280 days / 40 weeks.
(v) The sex chromosomes in a male and female embryo are:
Male - XY
Female - XX
Related Questions
Give scientific reasons for the following statements:
(i) Colour blindness is more common in men than in women.
(ii) Injury to medulla oblongata leads to death.
(iii) When an ovum gets fertilized, menstrual cycle stops temporarily in a woman.
(iv) Mature erythrocytes in humans lack nucleus and mitochondria.
(v) Blood flows in arteries in spurts and is under pressure.
The following diagram demonstrates a physiological process taking place in green plants. The whole set up was placed in bright sunlight for several hours. Study the diagram and answer the questions that follow:
(i) What aspect of the physiological process is being examined?
(ii) Explain the physiological process mentioned in (i) above.
(iii) Label the parts numbered 1 and 2 in the diagram.
(iv) Write a well-balanced chemical equation for the physiological process explained in (ii) above.
(v) What would happen to the rate of bubbling of the gas if a pinch of sodium bicarbonate is added to the water in the beaker? Explain your answer.
The given diagram shows a stage during mitotic division in an animal cell:
(i) Identify the stage. Give a reason to support your answer.
(ii) Draw a neat labelled diagram of the cell as it would appear in the next stage. Name the stage.
(iii) In what two ways is mitotic division in an animal cell different from the mitotic division in a plant cell?
(iv) Name the type of cell division that occurs during:
A. Growth of a shoot
B. Formation of pollen grainsA homozygous tall plant (T) bearing red coloured (R) flowers is crossed with a homozygous dwarf (t) plant bearing white (r) flowers :
(i) Give the genotype and phenotype of the plants of F1 generation.
(ii) Mention the possible combinations of the gametes that can be obtained from the F1 hybrid plant.
(iii) State the Mendel's law of Independent Assortment.
(iv) Mention the phenotypes of the offspring's obtained in F2 generation.
(v) What is the phenotypic ratio obtained in F2 generation?