Question

Сравните виды дробления Зиготы у ланцетника, амфибий и птиц

Answer 1

У ланцетника дробление полное равномерное.Клетки все одинаковы.

У амфибий полное не равномерное.
Клетки больше у вегетотивного полюса.

У птицы неполное дробление.
дробится только зародышевый диск.

Answer 2

Comparison of Zygote Cleavage in Lancelets, Amphibians, and Birds

When comparing the types of zygote cleavage in lancelets, amphibians, and birds, it is important to note that these organisms belong to different taxonomic groups and have distinct reproductive strategies. Here is a detailed comparison of the zygote cleavage in each group:

Lancelets (Branchiostoma): Lancelets, also known as amphioxus, are marine chordates that belong to the subphylum Cephalochordata. They have a simple body plan and reproduce sexually. The zygote cleavage in lancelets is characterized by the following features: - The zygote undergoes holoblastic cleavage, which means that the entire zygote divides during each cleavage event. - The cleavage is radial, resulting in daughter cells that are arranged in a radial pattern around the animal-vegetal axis of the zygote. - The cleavage planes are meridional, dividing the zygote into two equal-sized daughter cells. - The cleavage is synchronous, meaning that all the cells divide at the same time.

Amphibians: Amphibians are a diverse group of vertebrates that include frogs, toads, salamanders, and caecilians. They exhibit a variety of reproductive strategies, including external fertilization and internal fertilization. The zygote cleavage in amphibians is characterized by the following features - The zygote undergoes holoblastic cleavage, similar to lancelets. - The cleavage is radial in the animal hemisphere, but it becomes vegetal in the vegetal hemisphere. - The cleavage planes are meridional in the animal hemisphere, but they become equatorial in the vegetal hemisphere. - The cleavage is asynchronous, meaning that the cells divide at different times. - The cleavage is unequal, resulting in daughter cells of different sizes. - The cleavage pattern can vary among different amphibian species.

Birds: Birds are warm-blooded vertebrates that belong to the class Aves. They reproduce by laying eggs and exhibit internal fertilization. The zygote cleavage in birds is characterized by the following features - The zygote undergoes meroblastic cleavage, which means that only a portion of the zygote divides during each cleavage event. - The cleavage is discoidal, occurring only in the blastodisc region of the egg. - The cleavage planes are meridional, dividing the blastodisc into smaller cells. - The cleavage is asynchronous, with cells dividing at different times. - The cleavage is unequal, resulting in daughter cells of different sizes. - The cleavage pattern is influenced by the presence of the yolk, which is concentrated in the vegetal pole of the egg.

In summary, the zygote cleavage in lancelets, amphibians, and birds exhibits some similarities, such as holoblastic cleavage and meridional cleavage planes. However, there are also notable differences, such as the presence of asynchronous and unequal cleavage in amphibians and birds, and the discoidal cleavage in birds due to the presence of the yolk. These differences reflect the diverse reproductive strategies and embryonic development processes in these organisms.

I hope this comparison helps! Let me know if you have any further questions.