Zoology XII Chapter 2: Cleavage

Questions and Answers

What is the process called when Amoeba forms a protective layer around itself during unfavorable conditions?

Binary fission

Pseudopodia formation

Multiple fission

Encystment (correct)

In which type of fission is the plane of division oblique?

Transverse fission

Oblique binary fission (correct)

Simple fission

Multiple fission

What occurs first during the process of multiple fission?

Nucleus divides repeatedly (correct)

Feeding and growth of individual cells

Cytoplasm divides

Encystment happens

Which type of life cycle transition do the encysted forms of Amoeba undergo when conditions become favorable?

Multiple fission Signup and view all the answers

What characterizes the resulting cells from multiple fission in terms of size?

They are small and called pseudopodiospores Signup and view all the answers

What is binary fission in asexual reproduction?

The division of the parent body into two identical daughter individuals Signup and view all the answers

Which type of binary fission involves the division running along the transverse axis?

Transverse binary fission Signup and view all the answers

What occurs first during the binary fission process?

The nucleus divides Signup and view all the answers

Which organism is an example of simple irregular binary fission?

Amoeba Signup and view all the answers

During binary fission, the division of the cytoplasm is referred to as what?

Cytokinesis Signup and view all the answers

What is the result of asexual reproduction through binary fission?

Offspring that are genetically identical to the parent Signup and view all the answers

Which of the following statements about transverse and longitudinal binary fission is correct?

Transverse fission runs along the transverse axis of the individual Signup and view all the answers

Which of the following types of fission is NOT commonly seen in animals?

Regenerative fission Signup and view all the answers

What is the primary purpose of cleavage in the zygote development?

Conversion of the zygote into a multicellular structure Signup and view all the answers

What process follows the formation of the blastocyst?

Implantation Signup and view all the answers

Which structure is responsible for the temperature regulation necessary for sperm production?

Scrotum Signup and view all the answers

What is the function of the placenta during pregnancy?

To provide nutrients and oxygen from the mother to the fetus Signup and view all the answers

Which of the following stages involves the formation of specific tissues and organs?

Organogenesis Signup and view all the answers

Which of the following statements about the testes is incorrect?

They produce sperm at normal body temperature. Signup and view all the answers

What cellular transformation does gastrulation entail?

Formation of three primary germ layers Signup and view all the answers

What is parturition?

Expulsion of the fetus from the mother's womb Signup and view all the answers

Which structure temporarily stores spermatozoa and allows them to undergo physiological maturation?

Epididymis Signup and view all the answers

What connects the seminiferous tubules to the epididymis?

Vasa efferentia Signup and view all the answers

What forms the ejaculatory duct?

Vas deferens and duct of the seminal vesicle Signup and view all the answers

Which of the following is NOT an accessory duct associated with the male reproductive system?

Urethra Signup and view all the answers

Where do sperm enter after leaving the rete testis?

Vas deferens Signup and view all the answers

Which gland contributes most to the seminal fluid in the male reproductive system?

Seminal vesicle Signup and view all the answers

What is the role of the epididymis in sperm development?

Store and mature sperm Signup and view all the answers

Which structure collects sperm from the seminiferous tubules?

Rete testis Signup and view all the answers

What is the main method of reproduction demonstrated by daughter individuals via equal cell division?

Multiple fission Signup and view all the answers

In the context of Aurelia, what is the term used for the budding process that leads to young strobila?

Strobilation Signup and view all the answers

What key structure is involved in the formation of daughter nuclei during multiple fission in Amoeba?

Nucleus Signup and view all the answers

Which part of Aurelia is involved in the early development of ephyrae?

Tentacles Signup and view all the answers

What role does the cyst wall play in the reproductive process of Amoeba?

Protection during harsh conditions Signup and view all the answers

Which of the following structures is responsible for the feeding process in Aurelia?

Mouth Signup and view all the answers

What is the characteristic feature of the daughter individuals resulting from the multiple fission process?

They do not separate until maturity. Signup and view all the answers

In strobilation, what does the adult strobila produce?

Multiple juvenile forms Signup and view all the answers

Which structure aids in anchoring Aurelia to its substrate?

Adhesive disc Signup and view all the answers

Which type of fission specifically describes the process seen in some metazoan animals including Aurelia?

Transverse fission Signup and view all the answers

Study Notes

Human Reproductive System

Cleavage involves rapid mitotic divisions converting the zygote into a multicellular blastocyst.
Implantation is the attachment of the blastocyst to the uterine wall.
Placentation forms the placenta, allowing nutrient exchange between the fetus and mother.
The male reproductive system includes testes, accessory ducts, glands, and external genitalia.
Testes are ovoid organs housed in the scrotum for optimal sperm production at lower temperatures (2-3°C below body temperature).
The scrotum acts as a thermoregulator to support spermatogenesis.

Anatomy of the Male Reproductive System

Each testis is covered by a fibrous tunica albuginea, divided into 200-250 lobules.
Accessory ducts consist of rete testis, vasa efferentia, epididymis, and vas deferens.
Seminiferous tubules converge into the tubulus rectus, which delivers sperm to the rete testis.
The epididymis stores immature sperm for physiological maturation and motility improvement.
The vas deferens connects the epididymis to the ejaculatory duct, which then opens into the urethra.

Asexual Reproduction

Asexual reproduction types in animals include fission, budding, fragmentation, and regeneration.
Fission divides the parent body into identical daughter individuals, with five types recognized: binary, multiple, plasmotomy, strobilation, and sporulation.

Types of Fission

Binary Fission: Parent organism splits into two; nucleus divides via mitosis, followed by cytokinesis.
Transverse Binary Fission: Seen in organisms like Paramecium, where division occurs along the transverse axis.
Longitudinal Binary Fission: The organism divides along the longitudinal axis, examples include Vorticella.
Oblique Binary Fission: The division plane is oblique, common in dinoflagellates such as Ceratium.
Multiple Fission: The nucleus divides multiple times before the cytoplasm divides, producing numerous smaller individuals simultaneously.

Encystment in Amoeba

Amoeba can encyst under unfavorable conditions, forming a protective chitinous wall around itself.
Upon favorable conditions, the cyst wall absorbs water and breaks, liberating young amoebae (pseudopodiospores) to live independently.

Strobilation

A specialized form of reproduction in certain metazoans involves transverse fission, where segments (ephyrae) form in succession, illustrated in Aurelia.

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Description

This quiz focuses on the process of cleavage in the human reproductive system, specifically discussing how rapid mitotic divisions of the zygote lead to the formation of a multicellular structure. Test your understanding of this fundamental biological process in zoology.