Chapter+46,+47+and+38+Reproduction+and+Development

When contributing to the reading guide, follow these steps: 1) First complete the reading guide from the AP Portal on your own 2) Open the respected Collabortion Unit from the wiki in word 2) Choose a question from the wiki and write your response to the question in word and then copy it. Be sure to upload pictures and/or video for each question. 3) Click on the edit button and then go to the appropriate question and paste your answer below it. Sign your contribution with your first name and last initial 4) Save the page by selecting "Save with comment" from the Save dropdown. Enter a comment (e.g. "I answered chp 26 question 3" - Tom S.) then click Save.
 * TjeCollaboration Teams ** - Members share responsibility for posting refined answers to the guided readings - succinct, relevant, clear, and with __** pictures or a **** video **__ to compliment.

**Chapter 46 Animal Reproduction** Overview of Animal Reproduction

1.-Distinguish between asexual and sexual reproduction. Asexual reproduction is the creation of a new organism without the meeting of egg and sperm. In sexual reproduction, the fusion of haploid gametes forms a diploid zygote that further develops into an animal. AHC

2.-Describe several adaptive advantages of asexual reproduction. Discuss the conditions that may favor the occurrence of asexual reproduction. Adaptive advantages include, energy required to find a mate is conserved, stationary organisms such as coral do not need to rely on chance for sexual fertilization, and generally asexual animals can produce offspring at faster and more efficient rates. Stable environments are ideal for asexual production because offspring from asexual reproduction are clones of the parents and therefore lack genetic variation. If a environment is constantly changing, one environmental factor that's genetically unfavorable to the cloned animals can wipe out vast amounts of the population. E.g. a disease that the animals are susceptible to begins to spread and will likely wipe out the population because there are no immunities. AHC 3.-Describe an example of an animal life cycle that alternates between asexual and sexual reproduction.- Some protists or fungi alternate between sexual and asexual reproduction. The mold //Dictyostelium// performs cell division using binary fission in favorable conditions. When conditions are unfavorable, the mold cells fuse creating a larger cell. The "macrocyst" releases amoebic cells during germination that are meiotic recombinations between the two original mold cells. AHC 4.-Define //parthenogenesis// and describe the conditions that favor its occurrence. Note examples of invertebrate and vertebrate species that use this form of reproduction.- Parthenogenesis is a form of asexual reproduction. It is when the embryo can develop and grow without being fertilized. It occurs in many plants, some invertebrates such as nematodes, water fleas, and some bees, and in few vertebrates (some fish, amphibians, and reptiles). Parthenogenetic offspring are usually diploid, but can still be haploid depending if meiosis occurs. If it doesn't the offspring will usually be diploid. If it does go through meiosis, the offspring will only have half of mother's alleles.

ACHANG and DGORE

5.-Explain how hermaphroditism may be advantageous in sessile or burrowing animals that have difficulty encountering a member of the opposite sex.- A hermaphrodite has the ability to produce both egg and sperm. Therefore these animals can self-fertilize or any other similar animal can be a mate. So, these animals don't have to worry if the animal they meet is female or male.

ACHANG and DGORE

Mechanisms of Sexual Reproduction

6.-Compare and contrast internal vs external reproduction-- Internal fertilization is when the sperm and egg meet inside of the female. This is most common with land animals, such as humans, but some aquatic animals internally fertilize as well. Internal fertilization is more certain than external, meaning there is greater chance of the offspring surviving through pregnancy due to protection from the environment, and because of this fewer eggs need to be produced. External fertilization occurs mostly with aquatic animals and happens only in moist, wet locations. This is because the sperm and egg need to stay wet throughout pregnancy to avoid drying out. Externally fertilized eggs are in the open environment and exposed to predators, and for this reason a greater number of eggs must be produced in order to ensure survival. In both internal and external fertilization, sperm and egg meet to form a zygote. -Danny G. a.k.a. DG3

External Internal

Mammalian Reproduction

7.-Identify and give the function of each component of the reproductive system of the human male and female.--


 * Overview of Male Reproductive System Structure and Function**


 * **STRUCTURE** || **FUNCTION** ||
 * Cervix || During childbirth, contractions of the uterus will dilate the cervix up to 10 cm in diameter to allow the child to pass through. During orgasm, the cervix convulses and the external of dilates ||
 * Fallopian tubes || Egg transportation from ovary to uterus (fertilization usually takes place here). ||
 * Ovaries (female gonads) || Provides an environment for maturation of oocyte. Synthesizes and secretes sex hormones (estrogen and progesterone). ||
 * Urethra || Passage of urine. ||
 * Uterus || To house and nourish developing human. ||
 * Vagina || Receives penis during mating. Pathway through a woman body for the baby to take during childbirth. Provides the route for the menstrual blood (menses) from the uterus, to leave the body. May hold forms of birth control, such as an IUD, diaphragm, neva ring, or female condom ||
 * Endometrium || Contains glands that secrete fluids that bathe the uterine lining. ||


 * Overview of Female Reproductive System Structure and Function**

8.-Compare menstrual cycles and estrous cycles.-- One difference is that animals that have estrous cycles reabsorb the endometrium if conception does not occur during that cycle. Animals that have menstrual cycles shed the endometrium through menstruation instead. Another difference is sexual activity. In species with estrous cycles, females are generally only sexually active during the estrus phase of their cycle (see below for an explanation of the different phases in an estrous cycle). This is also referred to as being "in heat". In contrast, females of species with menstrual cycles can be sexually active at any time in their cycle, even when they are not about to ovulate.
 * **STRUCTURE** || **FUNCTION** ||
 * Bulbourethral glands || Secretion of gelatinous seminal fluid called pre-ejaculate. This fluid helps to lubricate the urethra for spermatozoa to pass through, and to help flush out any residual urine or foreign matter. (< 1% of semen) ||
 * Leydig cells (Interstitial cells) || Responsible for production of testosterone. Closely related to nerves. ||
 * Epididymis || Storage and maturation of sperm. ||
 * Penis || Male reproductive organ and also male organ of urination. ||
 * Prostate gland || Stores and secretes a clear, slightly alkaline fluid constituting up to one-third of the volume of semen. Raise vaginal pH.(25-30% of semen) ||
 * Scrotum || Regulates temperature at slightly below body temperature. ||
 * Seminiferous tubules || Meiosis takes place here, creation of gametes (sperm). ||
 * Sertoli cells || Cells responsible for nurturing and development of sperm cells, provides both secretory and structural support; activated by FSH. ||
 * Testes || Gonads that produce sperm and male sex hormones. Production of testosterone by Leydig cells in the testicles. ||
 * Urethra || Tubular structure that receives urine from bladder and carries it to outside of the body. Also passage for sperm. ||
 * Vas deferens || During ejaculation the smooth muscle in the vas deferens wall contracts, propelling sperm forward. Sperm are transferred from the vas deferens into the urethra. ||

9.-Describe the stages of the human female reproductive cycle.-- The 3 phases of your menstrual cycle are triggered by hormonal changes.

1. Menstrual period
On Day 1 of your cycle, the thickened lining (endometrium) of the uterus begins to shed. You know this as menstrual bleeding from the vagina. A normal menstrual period can last 4 to 6 days. Most of your menstrual blood loss happens during the first 3 days. This is also when you might have cramping pain in your pelvis, legs, and back. Cramps can range from mild to severe. The cramping is your uterus contracting, helping the endometrium shed. In general, any [|premenstrual symptoms] that you've felt before your period will go away during these first days of your cycle.

2. Follicular phase
During the follicular phase, an egg follicle on an ovary gets ready to release an egg. Usually, one egg is released per cycle. This process can be short or long and plays the biggest role in how long your cycle is. At the same time, the uterus starts growing a new endometrium to prepare for pregnancy. The last 5 days of the follicular phase, plus ovulation day, are your fertile window. This is when you are most likely to become pregnant if you have sex without using birth control.

3. Luteal (premenstrual) phase
This phase starts on ovulation day, the day the egg is released from the egg follicle on the ovary. It can happen any time from Day 7 to Day 22 of a normal menstrual cycle. During ovulation, some women have less than a day of red spotting or lower pelvic pain or discomfort (mittelschmerz). These signs of ovulation are normal.
 * If the egg is fertilized by sperm and then implants in (attaches to) the endometrium, a pregnancy begins. (This pregnancy is dated from Day 1 of this menstrual cycle.)
 * If the egg is not fertilized or does not implant, the endometrium begins to break down.

10.-Describe human oogenesis.

In simple terms, oogenesis is the formation, development, and maturation of an ovum. A developing egg is called an oocyte. Its differentiation into a mature ovum involves a series of changes whose timing is geared to the steps of meiosis in which the germ cells go through their two final, highly specialized divisions, as seen in the diagram below. Oocytes have evolved special mechanisms for obtaining progress through meiosis: they remain suspended in propphase I for a prolonged period while the oocyte grows in size, and usually they rest in metaphase II while awaiting fertilization. The process of oogenesis shown in the diagram is also taken apart in detail on the following video: http://www.youtube.com/watch?v=fyhl6Qcu5NQ -Tom Haile



11.-Describe spermatogenesis and the structure and function of mature sperm.--

Spermatogenesis is the formation and development of sperm in adolescent and adult males. All four daughter cells from meiosis develop into mature gametes. This process is continuous, as hundreds of millions of sperm are produced each day. Sperm divide and differentiate from spermatogonia to spermatocytes, and as they travel through the seminiferous tubules they pass through the spermatocyte stage and become spermatids. Mature sperm have a tail for movement, a mitochondrial mid piece for energy, and a head with an acrosome at the front. The acrosome is responsible for dissolving the jelly layer surrounding the egg before fertilization. http://bio1152.nicerweb.com/Locked/media/ch46/spermatogenesis.html - JH

12.-Describe three major differences between oogenesis and spermatogenesis.-- [|Spermatogenesis vs. Oogenesis]

EMILY

13.-Describe the influence of androgens on primary and secondary sex characteristics and behavior.--

Androgens are responsible for a man's voice to drop, facial and pubic hair to develop, and an increase in muscle mass. They also cause the appearance of primary sex characteristics such as the penis, seminal vesicles, and testes. Finally, androgens promote sexual behaviors and sex drive, in addition to an increase in aggressiveness. - JH

14.-Define //conception, gestation,// and //parturition.//--

Conception - Fertilization of an egg by sperm. Gestation - Pregnancy, carrying the young in the reproductive tract. Parturition - Action/process of giving birth - JH

15.-Describe the changes that occur in the mother and the developing embryo during each trimester of a human pregnancy.--

15.-List the various methods of contraception and explain how each works.

**Chapter 47 Animal Development** The Stages of Embryonic Development in Animals

16.-List the two functions of fertilization.-

17.-Explain how the fast and slow blocks to polyspermy function sequentially to prevent multiple sperm from fertilizing the egg.-

18. Describe the changes that occur in an activated egg and explain the importance of cytoplasmic materials to egg activation.- Activation occurs after a sperm fertilizes an egg. Once one sperm enters the egg for fertilization, fast block occurs about 1-3 seconds after the entry of the first sperm in order to deny entry to other sperm cells. Fast block occurs as the egg changes from a negative charge to a positive charge, therefore repelling the positive sperm cells away. In slow block, also known as the cortical reaction, the zona pellucida increases so the sperm cannot enter. Calcium releases from within the cell, causing a thickening in the zona pellucida. Mammals only have slow block. - Eli 19. Describe the general process of cleavage.- Cleavage is a succession of rapid cell division following fertilization. The process is as follows: the cells undergo S and M phase of the cell cycle (DNA replication and mitosis, respectively) but skip the G1 and G2 phase. What this ultimately achieves is dividing the cytoplasm of the zygote from one large to cell to many smaller cells called blastomeres. -Monika

20. Distinguish among meroblastic cleavage, holoblastic cleavage, and the formation of the blastoderm.- Meroblastic cleavage is an incomplete division of yolk-rick egg. Holoblastic cleavage is the complete division of eggs that have little to a moderate amount of yolk. The formation of the blastoderm is a result of meroblastic division. Since the yolk at one side of the egg prevents division, the blastoderm forms at the animal pole (opposite the vegetal pole) and forms an embryo around the yolk. -Monika

21. Describe the process of gastrulation and explain its importance. Explain how this process rearranges the embryo. List adultstructures derived from each of the primary germ layers.- http://www.youtube.com/watch?v=x-p_ZkhqZ0M This video is good at explaining the process of Gastrulation and how it rearranges the embryo. The importance of gastrulation is that it rearranges the embryo into three embryonic germ layers. It is those layers that will eventually become all the developed parts of an adult animal. The nervous system and the outer layer of the skin in adult animals develop from the ectoderm. The endoderm produces the lining of the digestive tract and associated organs (liver, pancreas). The mesoderm partially fills the space between the ecto and endoderm. The kidneys, heart, muscles, inner layer of the skin and most other organs develop from the mesoderm.- Jared Molk 22. Describe the process of organogenesis - Organogenesis is known as the process where the organ rudiments develop from the three different germ layers immediately after gastrulation where the body organs will develop during the first trimester. Unfortunately, during organogenesis, the human embryo can be exposed to various dangers, such as radiation or drugs that can cause birth defect. Overall, organogenesis causes more localized changes where the ectoderm, endoderm and mesoderm will change and alter into the internal organs of an organisms. These germ layers will be differentiated by the folds, splits and condensation. In this stage, the neural tube and notochord will develop in chordate animals and vertebrates, a neural crest is formed as well as are somites. Organogenesis will be different also in invertebrates, as their body plans diverge from vertebrates. -Daniel Kogan



23. Describe the events of cleavage in a mammalian embryo. Explain the significance of the inner cell mass.- Cleavage occurs once fertilization is complete, as various species will undergo rapid cell dividision. In cleavage, the cell cycle will consist of DNA synthesis and Mitosis and as result, cleavage partitions the cytoplasm of the fertilized egg intro blastomeres. The first 5-7 divisions of cleavage will produce the blastula, surrounded by the blastocoel. The number of cleavage divisions will vary among mammals but maintains a controlled pattern. As the zygote will continue to have rapid cell cycles without growth, blastomeres will be compacted to form a morula, before cleavage ends with forming the blastula. Cleavage can be either holoblastic, referring to the entire cleavage or meroblastic, which means only a partial cleavage. The vegetal pole involved in cleavage is the pole of the egg maintaining the highest concentration of yolk where the other pole opposite to that is the animal pole. Inner cell mass is clustered at one end of the blastocyst, a stage of the development where the embryo has more than 100 cells arranged around the central cavity. Soon, this inner cell mass will develop the embryo properly which are the source of embryonic stem cell lines. - DK

24. Explain the role of the trophoblast in implantation of a human embryo.- Trophoblasts are specialized cells of the placenta that play an integral role in embryo implantation and interaction with maternal uterus. The core of placental villi contain mesenchymal cells and placental blood vessels that are directly connected to the fetal circulation via the umbilical cord. This core is surrounded by two layers of trophoblast--a single layer of mononuclear cytotrophoblast that fuse together to form the overlying syncytiotrophoblast layer that covers the entire surface of the placenta. It is this syncytiotrophoblast that is in direct contact with the maternal blood that reaches the placental surface, and thus facilitates the exchange of nutrients, wastes and gases between the maternal and fetal systems.-Sabrina

25. Explain the functions of the extraembryonic membranes in mammalian development.- The yolk sac stores and provides nourishment for the developing embryo. The allantois stores the nitrogenous wastes of the embryo, which is the excreted matter. The amnion covers and protects the embryo, and the chorion covers the amnion, yolk sac and allantois. The placenta is formed from the endometrium of the mother. It functions to allow the exchange of substances between the fetus and the mother.- JLM

**Chapter 38 Plant reproduction and Development** Sexual Reproduction

26.-In general terms, explain how the basic plant life cycle with alternation of generations is modified in angiosperms.- Angiosperms use a unique process called double fertilization in which the male gametophyte produces two sperm cells that fertilize two cells within the female gametophyte. One fertilized cell develops into the new sporophyte, the embryo, and the other develops into a unique triploid endosperm. The endosperm feeds the developing embryo. For angiosperms, the diploid sporophyte generation is the dominant generation. - JLM

27.-List four floral parts in order from outside to inside a flower.- Sepal, petal, stamen, carpel []

Happy Valentine's Day! Ella P

28.-From a diagram of an idealized flower, correctly label the following structures and describe the function of each structure:

a. sepals b. petals c. stamen (filament and anther)d. carpel (style, ovary, ovule, and stigma)

Sepal-protects unopened floral buds. petal- attract insects and other pollinators so the flower can spread its seed. stamen- contains anther and filament. Microsporangia are inside anther, which produce pollen. Filament holds up anther. carpel- contains ovary, stigma, and style. Ovules are found inside the ovaries. Stigma captures pollen. Style holds stigma away from the ovary to decrease the likelihood of pollen contamination.

Ella P

29. Distinguish between:a. complete and incomplete flowersb. bisexual and unisexual flowersc. monoecious and dioecious plant species-

a) **Complete** flowers possess: sepals, petals, stamens, and pistils. A flower missing one or any of these features is **incomplete**.

b) **Bisexual** flowers have both male and female reproductive units, so both the stamen, carpel, and ovaries. **Unisexual** flowers possess only one.

c) in a way to promote variation, some plants are dioecious. **Dioecious** species have certain plants with staminate flowers(lacking carpels) and carpellate flowers(lacking stamens). These plants cannot self-fertilize.

-Philip
 * Monoecious** plants have also developed to promote variation. These species possess separate staminate and carpellate flowers, but on the same plant.

30. Explain by which generation, structure, and process gametes and spores are produced.

Plants go through an alternation of generations consisting of a sporophyte generation and a gametophyte generation. The sporophyte generation is diploid (2n) and the gametophyte generation is haploid (n). The sporophyte generation feeds into the gametophyte generation when meiosis takes place, producing haploid spores. Through mitotic division, this spore becomes a multicellular gametophyte. This gametophyte then produces haploid gametes through more mitotic divisions. Once fertilization due to sexual reproduction occurs (fusion of 2 gametes), the plant enters the diploid part of the cycle, the sporophyte generation. This generation begins with a zygote, which, through mitosis, produces a multicellular sporophyte. The diploid sporophyte then produced haploid spores through meiosis, starting the cycle again.

-Philip and Supritha

31. Describe the alternation of generations in flowering plants.-

The sporophyte generation is dominant in angiosperms. The microsporangia are the anthers, which, through meiosis, produce microspores. These microspores become male gametophytes. The megasporangia are the ovaries, which, through meiosis, produce megaspores. These megaspores become female gametophytes. Pollination occurs when the male gametophyte, pollen, is transferred to the female stigma; fertilization is the fusion of the male and female gametes. Angiosperms ungergo double fertilization; one sperm nucleus and egg form a 2n zygote and another sperm nucleus and 2 eggs form a 3n endosperm, which serves as the food supply for then 2n embryo.

-Philip and Supritha

32. Distinguish between pollination and fertilization.- Pollination is the spreading of the male pollen grain to the female flower while fertilization is the mutual joining of female and male gametes to form a zygote. Fertilization fuels embryo development in all plants and endosperm development in angiosperms.

http://www.youtube.com/watch?v=Lkkqj2FQAO Elena :)

33. Describe mechanisms that prevent self-pollination.- Some plants have only male (staminate) flowers and only female (pistillate) flowers, making it impossible for them to pollinate themselves when they don't have both female and male mechanisms. There is also something called self-imcompatibility which some plants have adapted to encourage outcrossing and diversity. This is when the pollen grain meets the stigma and then one of the following processes halts and a seed is never produced. Also, sometimes the stigma and the pollen mature at different times, meaning that an older stigma would not be able to be pollinated by immature pollen and matured pollen wouldn't be able to pollinate an immature stigma.

Elena :)

34. Outline the process of double fertilization. Explain the adaptive advantage of double fertilization in angiosperms.-

Double fertilization generally occurs in flowering plants (angiosperms) although it also occurs in several varieties of  gymnosperms. In both angiosperms and gymnosperms, the pollen tube contains two haploid (1n) sperm. In angiosperms, one sperm fuses with an egg to produce a diploid (2n) zygote in a process called fertilization. This zygote then divides repeatedly through mitosis and develops into a seed embryo. The second sperm fuses with two haploid polar nuclei to form a triploid (3n) nucleus termed the "primary endosperm nucleus." This process is called double fertilization because both sperm from the pollen tube fertilize either an egg or polar nucleus. The endosperm nucleus is not necessarily triploid; dependent upon the species, it may also be 2n, 5n, 9n or 15n. While the evolutionary significance is not clear, it has been hypothesized that because the endosperm nucleus is very active and divides quickly, it forms nutritive tissue that supports the seed. -Kellen []

35. Describe the development and function of the endosperm. Distinguish between liquid endosperm and solid endosperm.- The endosperm is the tissue inside the seed of angiosperms that is produced during the time of fertilization; it provides nutrition for the embryo in the form of starch, and, occasionally, oils and proteins. The endosperm is formed from the process of double fertilization in which one sperm fuses with an egg and the other sperm fuses with polar nuclei; the sperm that fuses with polar nuclei eventually develops into an endosperm. Most endosperm cells display polypoidy, with triploidy being the most common although endosperm cells vary from 1n to 15n. Nuclear endosperm formation is often referred to as liquid endosperm; repeated free-nuclear divisions take place and no cell wall is formed until after division. Coconut milk is an example of liquid endosperm. Cellular endosperm formation is often referred to as solid endosperm; cell wall formation occurs alongside nuclear divisions. Coconut meat is an example of solid endosperm. The primary purposes of endosperm include the transfer of nutrients from the mother plant to the embryo, seed dormancy, the abortion of seeds from genetically mismatched plants, and in some cases, the release of hormones such as cytokinins. -Kellen

36 . Identify the following structures and state a function for each:a. seed coat b. proembryo c. suspensor d. hypocotylse. radicle f. epicotyl g. plumule h. endosperm i. cotyledons j. shoot apex- a. A seed coat develops from the tissue originally surrounding the ovule. The seed coat in the mature seed can be a paper-thin layer, such as in a peanut, or something more substantial, such as in a coconut. The coat helps protect the embryo from injury and dehydration. b. A proembryo is a series of cells formed after fertilization within the ovule of a plant before formation of an embryo. c. Suspensors connect the embryo to endosperm, a placental mammal's umbilical cord. d. The hypocotyl is the stem of a germinating seedling found below the cotyledons and above the radicle. e. The radicle is the first part of the seedling to emerge from the seed during differentiation. It is the embryonic root of the plant. f. The epicotyl is the embryonic shoot above the cotyledons that usually develops into leaves. g. The plumule is the part of a seed embryo that develops into the shoot, bearing the first true leaves of the plant. h. Endosperm is the tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition. i. A cotyledon is a significant part of the embryo within the seed of a plant; may become first leaves of a seedling. j. The shoot apex is the terminal bud of a plant which consists of the apical meristem and the immediate surrounding leaf primordia.

-Sabrina 37 .Explain how a monocot and dicot seed differ.-

38 . Distinguish among simple, aggregate, and multiple fruit. Give an example of each type of fruit.-