Human eggs area)Alecithalb)Microlecithalc)Mesolecithald)MacrolecithalCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

Eggs are of 4 types regarding the amount of yolk present in them :
(i) Alecithal Egg : Almost free of yolk eg. most mammals like man.
(ii) Microlecithal Egg : Very small amount of yolk eg. Branchiostoma.
(iii) Mesolecithal Egg : Moderate amount of yolk eg. Frog’s egg
(iv) Macrolecithal Egg : Large amount of yolk eg. Reptiles, birds and egglaying mammals.

Answer

An alecithal egg is one which has a negligible amount of yolk or no yolk. Yolk provides the nutrition necessary for the development of the embryo and hence its presence is necessary for organisms that are oviparous. However, in humans, the developing embryo remains connected to the mother and obtains nutrition from the mother through the placenta. So, their egg has a negligible amount of yolk and are alecithal.

Answer

Human eggs

Human eggs, also known as ova or oocytes, are the female reproductive cells involved in sexual reproduction. These eggs are produced by the ovaries and have distinct characteristics based on their yolk content.

Alecithal eggs

The correct answer to this question is option 'A', which refers to alecithal eggs. Alecithal eggs are characterized by the absence of yolk or a very small amount of yolk. Let's dive deeper into the characteristics of alecithal eggs:

1. Lack of yolk: Alecithal eggs have a minimal amount of yolk or lack yolk altogether. Yolk is a nutrient-rich substance that supplies energy and nutrients to the developing embryo. In alecithal eggs, the yolk is either absent or present in such small quantities that it does not play a significant role in nourishing the developing embryo.

2. Small size: Due to the absence or minimal amount of yolk, alecithal eggs are relatively small in size compared to other types of eggs. The lack of yolk allows for a smaller overall size, making it easier for the egg to be transported through the female reproductive system.

3. External nourishment: Since alecithal eggs have limited or no yolk, they rely on external sources for nourishment. In humans, the developing embryo receives nutrients and oxygen through the umbilical cord, which connects the embryo to the placenta in the mother's uterus.

4. Mammalian reproductive strategy: Alecithal eggs are characteristic of mammals, including humans. Mammals have evolved to have internal fertilization and provide a nurturing environment for the developing embryo within the mother's body. The absence of a large yolk in alecithal eggs is advantageous for internal fertilization and the subsequent development of the embryo within the mother's uterus.

In summary, human eggs are alecithal, which means they have little to no yolk. This characteristic is essential for the mammalian reproductive strategy of internal fertilization and the subsequent development of the embryo within the mother's body.

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