please answer me..... anyone can answer.... please help.... 20 to 26... answer all my questions fast I will choose you as brainliest..
Answers
20. The kind of reproduction in which it is not necessary to have two parents to produce offspring. The reproduction of single-celled organisms through fission, and the production of spores in some plants and plantlike organisms, are examples of asexual reproduction.
In Bryophylum, reproduction occurs through asexual means, specifically, through vegetative propagation of leaves. The leaves of Bryophylum are broad possessing notches at its margins, these are the locations from which buds(notches) arise. The buds are termed as epiphyllous buds which have the potential to produce new plants having shoots, small leaves and adventitious roots. The newly formed plants can then detach from teh leaves to grow into a mature plant once it touches the soil.
In preparation for reproduction, the amoeba will withdraw its pseudopodia and form a spherical shape. Mitosis is observed in the nucleus, and the cytoplasm divides at the center of the cell and separates, forming two daughter cells. ... In both situations, the cell eventually dies without a nucleus
21.
1. Natural method: It involves avoiding the chances of meeting of sperms and ovum. In this method, the sexual act is avoided from day 10th to 17th of the menstrual cycle because, during this period, ovulation is expected and therefore, the chances of fertilization are very high.
2. Barrier method: In this method, the fertilization of ovum and sperm is prevented with the help of barriers. Barriers are available for both males and females. Condoms are barriers made of thin rubber that are used to cover penis in males and vagina in females.
3. Oral contraceptives: In this method, tablets or drugs are taken orally. These contain small doses of hormones that prevent the release of eggs and thus fertilization cannot occur.
4. Implants and surgical methods: Contraceptive devices such as the loop or Copper-T are placed in the uterus to prevent pregnancy. Some surgical methods can also be used to block the gamete transfer. It includes the blocking of vas deferens to prevent the transfer of sperms known as vasectomy. Similarly, fallopian tubes of the female can be blocked so that the egg will not reach the uterus known as tubectomy.
22.
We prefer a convex mirror as a rear-view mirror in vehicles because it gives a wider field of view, which allows the driver to see most of the traffic behind him. Convex mirrors always form a virtual, erect, and diminished image of the objects placed in front of it.
23.
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24.The resistance of the conductor depends on the following factors: The temperature of the conductor. The cross-sectional area of the conductor. Length of the conductor.
24.The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it becomes too hot and glows red. But the resistance of cord which is usually of copper or aluminum is very low so it does not glow
25,Decomposers feed on dead things: dead plant materials such as leaf litter and wood, animal carcasses, and feces. They perform a valuable service as Earth's cleanup crew. Without decomposers, dead leaves, dead insects, and dead animals would pile up everywhere.
26.Forests are a valuable resource providing food, shelter, wildlife habitat, fuel, and daily supplies such as medicinal ingredients and paper. Forests play an important role in balancing the Earth's CO2 supply and exchange, acting as a key link between the atmosphere, geosphere, and hydrosphere.
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