(a) How are variations useful for species if there is drastic alteration in the niches?
(b) Explain how the uterus and placenta provide necessary conditions for proper growth and development of the embryo after implantation?

Engage, explore, explain,elaborate and evaluate are five important 'Es' in relation to effective teaching of Science. To provide practical experiences to the students related to the concept of 'Necessary conditions for germination', a Science teacher asks them to do the following activites A. Soak seeds overnight and keep these in a wet cotton cloth. B. Observe the seeds after two days and record the changes. C. Read the book and attempt the given worksheet. Which of the five 'Es' given above are not being covered in the above activities given by the teacher ?

(a) Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and write its functions. (b) Name the parts of the human female reproductive system where fertilization occurs. (c) Explain how the developing embryo gets nourishment inside the mother's body.

(a). It is known that density rho of air decreases with height y as rho=rho_(0)e^(-y//y(_o)) ltb rgt where p_(o)=1.25kgm^(-3) is the density at sea level, and y_(o) is a constant. This density variation is called the law of atmospheres. Obtain this law assuming that the temperature of atmosphere remains a constant (isothermal conditions). Also assume that the value of g remains constant (b). A large He balloon of volume 1425m^(3) is used to lift a payload of 400 kg. Assume that the balloon maintains constant radius as it rises. How high does it rise? [take y_(o)=8000m and rho_(He)=0.18kgm^(-3) ]

Toyota follows certain well-defined business principles guiding its functioning. These are: 1. Honour the language and spirit of law of every nation and undertake open and fair corporate activities to be a good corporate citizen around the world. 2. Respect the culture and customs of every nation and contribute to economic and social development through corporate activities in local communities 3. To provide clean and safe products and to enhance the quality of life everywhere. 4. Create and develop advanced technologies and provide outstanding products and services that fulfil the needs of customers worldwide. 5. Foster a corporate culture that enhances individual creativity and teamwork value, while honouring mutual trust and respect between management and labour. 6. Pursue growth and harmony with global community through innovative management. 7. Work with business partners in research and creativity to achieve stable, long-term growth and mutual benefits and be open to new partnerships. These principles, will guide the company in its global vision 2010. This global vision envisages continuous innovations in future, use of environment friendly technologies, respecting and working with different sections of society and establishing an interactive relationship with society. How does management principles help an organisation to achieve its goals?

(a) Explain how the separation of oxygenated and deoxygenated blood is useful in humans ? (b) Why is double circulation of blood necessary in humans ?