Reproduction and Development in Animals

A comprehensive set of vocabulary flashcards covering key terms related to animal reproduction and development, suitable for exam review.

Homeostasis

The ability of an organism to maintain internal stability separate from its environment.

Surface-Area-to-Volume (SA/V) Ratio

The proportion between a cell’s surface area and its volume that influences diffusion rates and material exchange.

What is the correct order of Asexual reproduction?

Mitosis → Types: 1) Binary fission. 2) Simple mitosis (protists). 3) Fission, budding, parthenogenesis (animals) → Produces genetically identical progeny

What is the correct order of Sexual Production?

1) Mitosis. 2) Meiosis. 3) Modification → Gametogenesis → Fusion of gametes → Produces genetically different progeny

Mitosis

Eukaryotic cell division that produces two genetically identical daughter cells; basis of asexual reproduction and growth.

Meiosis

Two-step nuclear division that halves chromosome number, forming genetically diverse gametes for sexual reproduction.

Binary Fission

Asexual reproduction in which one prokaryotic cell divides into two identical cells.

Budding

Asexual reproduction where a miniature offspring grows on and detaches from the parent (e.g., hydra).

Regeneration

Formation of a complete organism from a body fragment, as seen in some anemones and starfish.

Parthenogenesis

Asexual process where females produce offspring from unfertilized eggs (e.g., some lizards, Daphnia).

Gametogenesis

The formation of gametes (sperm or eggs) via mitosis, meiosis, and cellular differentiation.

Spermatogenesis

Process in testes that produces haploid sperm; includes meiosis and maturation.

Oogenesis

Egg production in ovaries; yields one mature ovum and polar bodies after meiosis.

Testes

Male gonads where spermatogenesis and testosterone production occur.

Epididymis

Coiled tube atop each testis where sperm mature and are stored.

Vas Deferens

Duct that transports sperm from the epididymis to the ejaculatory duct.

Seminal Vesicles

Paired glands adding fructose-rich fluid to semen to nourish sperm.

Prostate Gland

Male accessory gland that secretes alkaline fluid contributing to semen volume and pH.

Bulbourethral (Cowper’s) Glands

Glands that release mucus-rich pre-ejaculatory fluid for lubrication and pH neutralization.

Semen

Mixture of sperm and accessory fluids ejaculated from the male reproductive tract.

What are the component of the mammalian sperm?

1) Head

2) Neck

3) Midpiece

4) Tail with flagellum

Head of sperm

The head contains the nucleus and an enzyme, acrosome, for penetrating the egg, allowing the sperm to penetrate the barrier

Neck of sperm

The neck contains one centriole that will combine with the egg’s centriole to form a centrosome, making the formation of the spindle apparatus during mitosis

Midpiece of sperm

The midpiece contains mitochodia, which produce ATP tp power movement

Tail with flagellum

Tail-like structure whose whip-like motion propels sperm.

Acrosome

Enzyme-filled cap on sperm head that facilitates penetration of egg coverings.

Centrosome

Organelle formed by sperm and egg centrioles; organizes spindle during mitosis in zygote.

Ovary

Female gonad where oocytes undergo meiosis and hormones (estrogens, progesterone) are produced.

Oviduct (Fallopian Tube)

Duct receiving ovulated egg; usual site of fertilization; transports embryo to uterus.

Uterus

Muscular organ where embryonic and fetal development occurs in mammals.

Cervix

Narrow neck of uterus that opens into the vagina.

Vagina

Muscular canal functioning as birth canal and copulatory organ in females.

Estradiol

Primary estrogen produced by ovarian follicles; promotes endometrial growth.

Progesterone

Ovarian hormone from corpus luteum that maintains uterine lining for pregnancy.

Follicle-Stimulating Hormone (FSH)

Anterior pituitary hormone stimulating spermatogenesis and follicle development.

Luteinizing Hormone (LH)

Anterior pituitary hormone triggering ovulation and stimulating testosterone production.

Zona Pellucida

Thick glycoprotein layer surrounding mammalian oocyte beneath corona radiata.

Corona Radiata

Outer layer of granulosa cells encasing the mammalian oocyte.

Fertilization

Fusion of haploid sperm and egg nuclei to form a diploid zygote.

External Fertilization

Gametes unite outside the bodies of parents, typically in aquatic environments.

Internal Fertilization

Sperm are deposited inside or near female reproductive tract, common in terrestrial animals.

Acrosomal Reaction

Release of acrosomal enzymes when sperm contacts egg, enabling penetration of protective layers.

Polyspermy

Fusion of more than one sperm with an egg; prevented by fast and slow blocks like the fertilization envelope.

Fertilization Envelope

Lifted layer that forms around zygote after sperm entry to block additional sperm.

Cleavage

Rapid mitotic divisions of zygote that partition cytoplasm into smaller blastomeres without growth.

Blastomere

Any cell resulting from the early cleavage divisions of the embryo.

Blastula

Hollow ball of blastomeres produced at the end of cleavage.

Blastocyst

Mammalian blastula consisting of trophoblast, blastocoel, and inner cell mass.

Trophoblast

Outer blastocyst layer that contributes to placenta formation.

Gastrulation

Morphogenetic process that rearranges blastula into a three-layered gastrula with germ layers.

Blastopore

Opening formed during gastrulation through which cells move into the embryo interior.

Germ Layers

Primary embryonic tissues—ectoderm, mesoderm, endoderm—that give rise to all organs.

Ectoderm

Outermost germ layer forming epidermis, nervous system, cornea, and mouth/rectum lining.

Mesoderm

Middle germ layer forming muscle, skeleton, circulatory, excretory, and reproductive systems.

Endoderm

Innermost germ layer forming gut lining and associated organs like liver and pancreas.

Notochord

Rod-like mesodermal structure that signals neural development and supports embryo.

Neural Tube

Ectoderm-derived tube that develops into the brain and spinal cord.

Somite

Segmented blocks of mesoderm flanking the neural tube that form vertebrae, ribs, dermis, and limb muscles.

Organogenesis

Series of cell movements and differentiation events that build tissues and organs from germ layers.

Viviparous

Reproductive mode in which embryo develops inside mother and receives nourishment from her body.

Oviparous

Reproductive mode in which fertilized eggs are laid outside the mother’s body, developing externally.

Neurulation

Stage of embryogenesis where ectoderm folds to create the neural tube.

Genetic Variation

Diversity of alleles within a population, enhanced by sexual reproduction and beneficial for evolution.

What are the main difference between sexual and asexual reproduction in animals?

Sexual reproduction two parents to produce genetic diverse offspring, while asexual reproduction involves a single parent producing genetically identical offspring.

What are the evolutionary advantage and disadvantages of each reproductive strategy?

Sexual reproduction's evolutionary advantage is increased genetic diversity, allowing for better adaptation to changing environments and disease resistance, but it's energetically costly and requires finding a mate; conversely, asexual reproduction's advantage lies in rapid population growth and efficiency in stable environments, but it lacks of genetic diversity, making populations vulnerable to environmental shifts and diseases.

Describe the process of spermatogensis: where does it occur, and what are the main steps?

Spermatogenesis is the process of male gamete (sperm) development, occurring in the seminiferous tubules of the testes, and involves three main steps: mitotic proliferation of spermatogonia (spermatocytogenesis), meiotic division of primary and secondary spermatocytes to form haploid spermatids (spermatidogenesis), and the morphological transformation of spermatids into mature spermatozoa (spermiogenesis).

Describe the process of oogenesis: how does it differ from spermatogensis in timing and ouput?

Oogenesis is the process of female gamete (ovum) development that begins prenatally, is arrested at various stages, and typically yields one large, nutrient-rich ovum and multiple polar bodies per meiotic event; whereas spermatogenesis is the continuous production of four small, motile sperm from each primary spermatocyte, beginning at puberty and continuing throughout a male's life.

What are the steps of fertilization in animals?

Fertilization in animals involves sperm activation, chemotaxis towards the egg, the acrosome reaction, fusion of sperm and egg membranes, blocks to polyspermy, egg activation, and finally, the fusion of parental pronuclei to form a diploid zygote.

What mechanisms prevent polyspermy?

Polyspermy is prevented by: the rapid fast block, an electrical depolarization of the egg membrane immediately upon sperm fusion, and the slower but permanent slow block (cortical reaction), which involves the release of cortical granule contents that modify the egg's outer layers to block further sperm entry.

What are the stage of early embroyonic development (cleavage, blastula, gastrulation, neurulation)?

Early embryonic development proceeds through cleavage, rapid cell division forming a multicellular embryo; blastulation, the formation of a hollow ball of cells called a blastula; gastrulation, the rearrangement of cells into three primary germ layers; and neurulation, the development of the neural tube which becomes the central nervous system.

Define and compare the three germ layer: ectoderm, mesoderm, and endoderm.

The three primary germ layers: ectoderm, the outermost layer, mesoderm, the middle layer, and endoderm, the innermost layer, are distinct embryonic tissues formed during gastrulation that ultimately differentiate to give rise to all the various tissues and organs of the adult animal.

Which hormone regulate male and female reproductive function?

In both sexes, GnRH, FSH, and LH regulate reproductive function, while testosterone is the primary sex hormone in males, and estrogens and progesterone are the primary sex hormones in females.