1.) Describe human male and female gametes,
2.) What do you mean by binary fission?
3)How does a new born baby have characters of both his father and mother?
4.) Explain different types of fertilisation
5) What are the primary sex organs in human females? Explain their function.
6.) Explain how fertilisation takes place in frog.
7.) How is an embryo developed from a zygote in
human female?
8) How does the fertilised egg develops into a
new organism in case of hen?
Answers
Answer:
1. Male Gametes - In humans, the male gametes decide the sexuality of the offspring.
Female Gametes - Female gametes do not determine sexuality in human.
2. Ameoba reproduces asexually by a method called binary fission. The nucleus of Amoeba elongates and finally divides into two daughter nuclei. The cytoplasm of the cell then divides resulting in the formation of two daughter cells.
3. Though the mother gives birth to a baby, fertilization involves the fusion of gametes from both the parents. Hence, character is obtained by both the parents. The zygote, therefore has both father and mother's contribution. Since the zygote develops into the baby, it has characters of both parents.
4. Animals also produce gametes for fusion. But the fusion of gametes may take place inside or outside the body. Based on this, fertilization is of two types – internal and external fertilization.
5. Ovaries: The ovaries are small, oval-shaped glands that are located on either side of the uterus. The ovaries produce eggs and hormones. Fallopian tubes: These are narrow tubes that are attached to the upper part of the uterus and serve as pathways for the ova (egg cells) to travel from the ovaries to the uterus.
6. Typically, frogs lay eggs. This process usually occurs through external fertilization, where the female releases her eggs from her body into water. Then, the male releases his sperm to fertilize them. However, a few species of frog use internal fertilization.
7. First, the zygote becomes a solid ball of cells. Then it becomes a hollow ball of cells called a blastocyst. Inside the uterus, the blastocyst implants in the wall of the uterus, where it develops into an embryo attached to a placenta and surrounded by fluid-filled membranes.
8. Internal fertilisation take place in hen also. After fertilisation takes place inside the body of the hen, the fertilised egg or zygote divides repeatedly to form embryo which travel down the oviduct. As it travels down the oviduct, many protective layers are formed around the embryo.