Videos
Introduction:
A zygote is a single-celled eukaryotic cell that is formed as the result of fertilization between two gametes. It undergoes mitosis to form an embryo that further develops into a multi-celled eukaryotic organism. The division of cells in the early embryonic stage is known as cleavage.
Answer to Problem 1TYK
Correct answer:
The major contributors to the cleavage development of zygotes are the egg nucleus and the yolk.
Explanation of Solution
Justification/explanation for the correct answer:
Option (d) states that the egg nucleus and the yolk are the major contributors to the cleavage patterns. The cleavage of the embryo occurs depending upon the amount of egg yolk present in the blastula (embryo after cleavage division is known as blastula). These cleavages can be holoblastic (total cleavage) or meroblastic cleavage (partial cleavage) that depends upon the amount of yolk present in the egg and the positioning of the nucleus in the egg. Hence, option (d) is correct.
The explanation for the incorrect answer:
Option (a) is given as sperm and egg cytoplasm. The cytoplasm is not the major contributing factor to the cleavage as the cleavage is mainly classified on the basis of the amount of yolk that is present in the egg. So, it is an incorrect option.
Option (b) is given as sperm and egg chromosomes. The chromosomes have nothing to do with the cleavage patterns. The chromosomes of the sperm and the egg consist of the genetic makeup of the embryo. So, it is an incorrect option.
Option (c) is given as ribosomes and mitochondria. These have an important role in the translation (expression of genetic material or formation of proteins) process and not in the cleavage divisions. So, it is an incorrect option.
Option (e) is given as pigments. Pigments can only be present after the genetic material expresses itself. The yolk and the egg nucleus contribute to the cleavage patterns of a zygote. So, it is an incorrect option.
Hence, options (a), (b), (c), and (e) are incorrect.
Therefore, it can be concluded that the cleavage patterns help in the organization and the development of different regions of the embryo or the blastula and turn it into a specialized region for the functioning of an organism. This depends on the amount of yolk present and the positioning of the nucleus in an egg and are thus, classified accordingly.
Want to see more full solutions like this?
Chapter 50 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Which of the following is true about Cleavage? Choose all possible answers a. At the end of cleavage, a 32-cell zygote called morula is formed. b. The angle and timing of mitotic spindle influence the pattern of embryonic cleavage. c. Cleavage is a series of mitosis that happens after the formation of zygote. d. The yolk protein is essential in determining where cleavage can occurarrow_forwardWhich of the following plays the greatest role in determining how cytoplasmic division occurs during cleavage? a. Number of chromosomes b. Amount of yolk c. Orientation of the vegetal pole d. Sex of the zygotearrow_forwardCleavage... A. Is a developmental stage consisting of a cell layer surrounding a fluid-filled space B. Is a specialized form of cell division that partitions the cytoplasm of a fertilized egg C. Refers to the fusion of haploid gametes to give a diploid zygote D. Produces an embryo with either two or three distinct cell layers E. None of the abovearrow_forward
- Gastrulation... A. Is a specialized form of cell division that partitions the cytoplasm of a fertilized egg B. Refers to the fusion of haploid gametes to give a diploid zygote C. Produces an embryo with either two or three distinct cell layers D. Is a developmental stage consisting of a cell layer surrounding a fluid-filled space E. None of the abovearrow_forwardWhich of the following is false? a. The endoderm, mesoderm, ectoderm are germ layers. b. The trophoblast is a germ layer. c. The inner cell mass is a source of embryonic stem cells. d. The blastula is often a hollow ball of cells.arrow_forwardWhich of the following statements CORRECTLY describes the contribution of sperm to thezygote for most vertebrate species?A. flagella, acrosome vesicle,B. mitochondria, haploid DNAC. centriole, haploid DNAD. acrosome vesicle, mitochondriaarrow_forward
- An individual has the chromosomal makeup XX and sexual differentiation proceeds normally. Which of the following would be the case? a. Mullerian ducts will degenerate b. Estrogen promotes development of the vagina c. Anti-Mullerian hormone is present d. Wolffian ducts will develop e. There will be no formation of fetal testesarrow_forwardWhich of the following statements is incorrect?a. The placenta secretes hormones such as progesterone, hCG, and estrogen.b. Embryonic tissue and maternal tissue forms the placenta.c. The chorion supplies nutrients to the embryo by diffusion.d. The umbilical cord is formed by one artery and two veinsarrow_forwardWhich of the following is not true about starfish eggs? Choose all possible answers a. eggs are fertilized prior to completion of the first meiotic divisions. b. eggs are generally less yolky and therefore cleave meroblastically. c. first two cleavage planes are meridional d. Each quartet (blastomeres) occupies a plane lying perpendicular to the animal-vegetal axis. e. All are true about the starfish eggs.arrow_forward
- Egg and sperm cells are... A. Gametes B. Diploid C. Somatic cells D. Zygotesarrow_forwardWhich of the following structure develops into only the fetus? A. Blastocyte B. Zygote C. Trophoblast D. Inner cell massarrow_forwardWhich of the following statements does NOT correctly describe the similarities and differences between male and female reproductive systems? Select one: a. Millions of mature sperm are produced on a daily basis, whereas single mature ovum is released every 28 days. b. Meiosis is completed in eggs after fertilization begins, whereas a mature sperm has completed meiosis prior to fertilization. c. Eggs and sperm contain exactly half of the genetic material of a normal somatic cell. Many zygotes with an abnormal number of genetic material often do not successfully implant. d. Eggs and sperm can survive for 3 to 5 days in the Fallopian tubes.arrow_forward
Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning