(a) Write the function of following parts in human female reproductive system: (i) Ovary (ii) Oviduct (iii) Uterus (b) Describe in brief the structure and function of placenta. OR (a) A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it. (b) Why do stars twinkle? Explain. OR (a) Write the function of each of the following parts of human eye: (i) Cornea (ii) Iris (iii) Crystalline lens (iv) Ciliary muscles (b) Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an astronaut on the Moon? Give reason to justify your answer. OR (a) State Fleming’s left hand rule. (b) Write the principle of working of an electric motor. (c) Explain the function of the following parts of an electric motor. (i) Armature (ii) Brushes (iii) Split ring

(a) Functions of Parts of the Human Female Reproductive System

1. Ovary:

• Production of Gametes: It produces the female germ-cells or gametes called eggs (ova).
• Hormone Secretion: It secretes essential female sex hormones, namely estrogen and progesterone, which regulate secondary sexual characteristics and prepare the body for pregnancy.

1. Oviduct (Fallopian Tube):

• Passage for Egg: It receives the egg released by the ovary and carries it towards the uterus.
• Site of Fertilization: It is the specific site where the male gamete (sperm) meets and fuses with the female gamete (egg) to form a zygote.

1. Uterus:

• Implantation: It provides the site for the attachment and implantation of the developing embryo.
• Nourishment and Development: Its muscular walls expand to accommodate, protect, and support the developing fetus during the gestation period.

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(b) Structure and Function of the Placenta

#### Structure:

• The placenta is a specialized disc-like tissue embedded deep within the uterine wall of the mother.
• On the embryo's side, it contains numerous finger-like projections called villi.
• On the mother's side, it contains blood spaces that surround these villi, maximizing the contact area.

#### Function:

• Nutrient and Oxygen Supply: It provides a large surface area for glucose, oxygen, and other essential nutrients to pass from the mother's blood to the developing embryo.
• Waste Removal: It allows metabolic waste products generated by the growing embryo to be transferred into the mother's blood for excretion.