Which of the following statements regarding animal development is/are correct? Select True or False for each statement. T/F The neural tube forms after organogenesis is complete T/F The blastocyst is formed during cleavage T/F During cleavage, the zygote divides rapidly without growth, forming a mass of cells T/F Animals have two germ layers

Verified step by step guidance

1. Step 1: Let's go through each statement one by one. The first statement is 'The neural tube forms after organogenesis is complete'. This statement is False. The neural tube, which eventually forms the brain and spinal cord, develops during the process of organogenesis, not after it.
2. Step 2: The second statement is 'The blastocyst is formed during cleavage'. This statement is True. The blastocyst is indeed formed during the process of cleavage, which is a series of rapid cell divisions that occur after fertilization.
3. Step 3: The third statement is 'During cleavage, the zygote divides rapidly without growth, forming a mass of cells'. This statement is True. During cleavage, the zygote does divide rapidly without growing in size, resulting in a mass of cells.
4. Step 4: The final statement is 'Animals have two germ layers'. This statement is False. While some animals, like cnidarians and ctenophores, have two germ layers (ectoderm and endoderm), most animals, including all vertebrates, have three germ layers (ectoderm, mesoderm, and endoderm).
5. Step 5: So, to summarize, the answers are: False, True, True, False.

Key Concepts

Neural Tube Formation

The neural tube is a structure that forms during early embryonic development, specifically during the process of neurulation. It develops from the ectoderm and is crucial for the formation of the central nervous system. The statement that the neural tube forms after organogenesis is complete is incorrect, as it actually forms before organogenesis begins.

Blastocyst Formation

The blastocyst is a hollow sphere of cells that forms during the early stages of embryonic development, specifically after the cleavage stage. Cleavage involves rapid cell division of the zygote without significant growth, leading to the formation of a multicellular structure. Therefore, the statement that the blastocyst is formed during cleavage is true.

Germ Layers in Animals

Germ layers are the primary layers of cells that form during embryonic development and give rise to all tissues and organs. Most animals develop three germ layers: ectoderm, mesoderm, and endoderm. The statement that animals have two germ layers is generally false, as most complex animals are triploblastic, having three germ layers.