Gas Exchange (Bio) PDF

Gas Exchange Assignment: How does asexual differ from sexual reproduction? What are the steps in sexual reproduction among animals? Surviving in thin air The high mountains of the Himalayas have claimed the lives of even the world’s top climbers The air at the highest peak is...

Gas Exchange Assignment: How does asexual differ from sexual reproduction? What are the steps in sexual reproduction among animals? Surviving in thin air The high mountains of the Himalayas have claimed the lives of even the world’s top climbers The air at the highest peak is low in oxygen that most people would pass out instantly if exposed to it Respiration Interchange of O2 and CO2 (organisms - environment) Provides O2 for cellular respiration and removes waste product (CO2) O2 is important because its the last electron acceptor or else we will not make much ATP. O2 comes from photolysis in photosynthesis mechanisms Mechanisms in Gas Exchange Gas exchange involves breathing (respiratory system) There is then a transfer of gases by the circulatory system There is an exchange of gases with the body cells Gas Exchange in Animals UNICELLULAR ORGANISMS Do not have blood vessels as they don’t have much space in their bodies Exchange gasses through diffusion Open transport system MAMMALS Mammalian lungs contain alveoli (small air sacs) where gas exchange takes place Whales and dolphins -> blowholes (allows them to take breaths by exposing the top of their head to air while they are swimming in water) Closed transport system (blood stays in blood vessels; hence, it’s bad if there is internal bleeding) REPTILES Similar to mammals Have larger “alveoli” Varanid - breath with their cheeks (buccal pumping) Exception: sea-snakes (they do gas exchange through their skin) Closed transport system AMPHIBIANS Balloon-like lungs Gas exchange takes place on the moist skin Gas exchange usually happens when they are in water. CO2 is diffused out of their skin and oxygen is absorbed from the water. They can also do buccal pumping Closed Transport System INSECTS Trachea-breathing organ Air goes to spiracles (tiny holes) on their skin Open transport system (because instead of blood, they have hemolymph) FISH Have gills - environmental adaptation so they can live in water Gills are protected by flaps of operculum made up of lamellae Lamellae contain capillaries Lung fish are different because they have lungs derived from the swim bladder, an organ used for buoyancy in most bony fishes which is connected to their alimentary tracts. These air breathing organs are covered by honeycomb like cavities, supplied with blood vessels. Closed transport system Gas Exchange in Plants ROOTS Happens in root hairs Root hairs increase surface area Requires soil to be aerated and moist Root hairs are almost always turgid because their solute potential is greater than that of the surrounding soil because mineral ions are actively pumped into the cell LEAVES Stomata (Holes) Stomata is found under the leaves but can be found in some stems STEM Lenticels (holes) Not all plants have lenticels One of the pores on woody plants that allows gas exchange between environment and internal tissues TYPES OF PLANTS BASED ON THEIR LIVING ENVIRONMENTS Xerophytes - dry environments (succulents, cactus, mango tree, aloe, agave, hworthia) Hydrophytes - on surface of water (lotus, water lily) Halophytes - saline water (mangroves) MANGROVES Have pneumatophores which are also called aerial roots. When submerged in water, these roots stay on top of water to be able to exchange gas Their roots are really impermeable so salt from these saline water can’t get into the roots They also stop their stomata from opening too many times to be able to stop water loss in leaves Sexual Reproduction in Plants Reproduction - the biological process by which organisms give birth or give rise to a new organism. This process is seen in all living organisms - both plants and animals. Parts of a flower: 1. Sepal The green leaf-like structure protecting the bud as the flower develops Collectively, sepals are called calyx 2. Petal The usually brightly-colored part of the flower Collectively, petals are called corolla 3. Stamen Male organ of the flower Long, filamentous structure The bulging tip is called the anther The anther contains the pollen grains 4. Pistil Female organ Made up of a single carpel or a group of fused carpels A carpel is a vase-like shaped structure which contains the bulging ovary, the slender stalk called style, and the stigma with a sticky tip PLANT REPRODUCTION (ALTERNATION OF GENERATIONS) The haploid gametophyte generation gives rise to the dipole sporophyte generation. The gametophyte forms the gametes which will have fusion to form zygote which undergoes mitosis to give rise to the sporophyte. It will then undergo meiosis to create the spores which are haploid cells. They will undergo mitosis again to give rise to gametophyte SEXUAL REPRODUCTION IN PLANTS Angiosperms - flowering plants Happens in the sexual organs of plants found in flowers Diploid sporophyte generation produces haploid gametophyte generation Male gametophyte 0 gives rise to pollen grains (developed from microspores) Female gametophyte - embryo sac (developed from megaspore) VARIATION OF PLANTS (FLOWER) Monoecious (the same plant, different, flowers) DIOECIOUS (separate plants There is also the hermaphrodite flowers wherein in the same flower, we can find the male and female parts STAGES OF SEXUAL REPRODUCTION 1. Pollen and egg formation (note: pollen contains the sperm) Diploid microspores -> meiosis -> haploid microspores Further mitotic divisions will form pollen grains with a generative cell and a vegetable / tube cell. Pollen tubes will form from the vegetative. Tube cell while the generative cell will divide to form 2 sperm cells  In each ovule, a megaspore mother cell (2n) undergoes meiosis to produce 4 haploid megaspores In most plants, only one haploid cell will continue while the three cells degenerate to form the embryo sac (n). It then undergoes mitosis three times We now have the embryo sac with 2 polar nuclei and egg cell Overview of pollen and egg formation:  The pollen created is sometimes manufactured by people to become supplements but some people are allergic to it. 2. Pollination Involves the transfer of pollen grains from the stamen to the stigma Type of pollination: 1. Self-pollination (same flower) 2. Cross-pollination (diff plants and flowers) a. Some plants have developed a mechanism to prevent self pollination because it reduces genetic variability Agents of pollination: 1. Wind 2. Water 3. Animals 3. Fertilization Pollen sticks to the gluey sugary substance covering the stigma A pollen tube forms and grows into the stigma, own the style and into the ovary. The tip of the pollen bursts to release the two sperm cells The sperm cells migrate down the pollen tube One pollen unites with the egg cell, forming a zygote The other pollen fertilizes with the two polar nuclei at the center of the embryo sac which produces a triploid (3N) primary endosperm. The zygote will undergo mitotic divisions The primary endosperm will develop into endosperm which provides nourishment for the embryo  4. Seed dispersal and germination Agents of dispersal ○ Wind (dandelion) ○ Water (acorn, coconut) ○ Animal (birds, bats) ○ Explosion (pea) Germination - the development of a plant from a seed or spore after a period of dormancy ○ Optimal condition (water, gases, nutrients) ○ Starts with plant embryo (root, stem portion, and one or more cotyledons (the first leaves) 1,042 × 745 ASEXUAL REPRODUCTION IN PLANTS Produces identical offspring from a single plant (no egg and sperm) Eliminates genetic recombination (advantageous) adapted to their environment and genetic variation is not necessary However, it's possible that the species will be wiped out because there's not variation 1. Natural Vegetative Reproduction A reproduction achieve through the plants’ vegetative parts or specialized structures Tubers, corns, rhizomes, shoots, suckers, stolons or runners, bulbs, corms leaf buds Runners or stolons ○ Are long, horizontal stems that run along the surface soil ○ Have nodes or regions where new shoot system and root system can be produced above or below them (e.g. strawberries, bermuda gradd) Rhizomes  ○ Underground stems that allow some plants to form a network and produce their kind ○ Have nodes from which new plants arise ○ E.g. irises, ginger, asparagus Tubers ○ Expanded thickened portions of a rhizome branch ○ Specialized for storage and reproduction (e.g. potato, yam, cassava) Bulbs and corms ○ Short underground stems ○ Corms are internally structures with solid tissues ○ bulbs are mostly made up of layered fleshy scales that are modified leaves ○ E.g. lilies, garlic, onions Leaf buds ○ Leave modified for reproduction ○ E.g. kalanchoe daigremontiana Sprouts or suckers ○ Plant growing not from a seed but from a meristem of the root at the base or at a certain distance from a tree or shrub ○ E.g. guava, apple 2. Artificial Propagation Methods Cutting ○ Breaking a piece of plant and sticking it to water ○ New roots or shoots may grow ○ E.g. sugarcane, apple, ornamental plants Grafting ○ Attached a piece of stem from one plant to a root or root bearing stem or another plant ○ Root-bearing host is called stock ○ The grafted part is called as scion  Tissue culture ○ Growing of plant tissue sin an artificial liquid or solid culture media ○ Provides an alternative means to grow new plants in mass number (e.g. carrots) Animal Reproduction ASEXUAL REPRODUCTION IN ANIMALS A single parent produces offspring; does not need sex cells Offspring is identical to parents Advantage: short time (less energy) Disadvantage: lack genetic variation TYPES OF ASEXUAL REPRODUCTION 1. Binary Fission - exact copy through mitosis Types: ○ Regular ○ Longitudinal ○ Transverse Examples: paramecium and bacteria 2. Budding A new organism develops from an outgrowth or bud due to cell division at one particular site The new organism remains attached as it grows, separating from the parent organism only when it is mature. Ex. budding hydra 3. Fragmentation - parent splits into pieces (ex. planaria) 4. Regeneration - renewal, restoration, and growth that makes organisms 5. Parthenogenesis - growth and development of embryos without fertilization (ex. Bees, especially drone bees) SEXUAL REPRODUCTION IN ANIMALS Animals may be: 1. Dioecious (one organism has a male part while the other has a female part) 2. Hermaprodites (earthworms and some fishes because they have both the male and female parts) 3. Sequential hermaprodites (can change their sex based on the season or the time) Steps in sexual reproduction: 1. Gametogenesis Production of gametes in gonads (testes and ovaries) 2. Spawning Bringing of gametes together  3. Fertilization Union of male and female gametes (internal or external) External fertilization - “informal fertilization”; happen outside the body, common in fish and amphibians Internal fertilization - takes place inside the body ○ Requires copulation (physical union that aids in the delivery of sperm to the female's body); ex. Chickens 4. Formation of zygote or fertilized egg Reptiles and fish deposit their fertilized eggs in the water to develop (oviparous); ex. Snails Viviparous, are animals that carry their young inside their body until their young are mature enough to be born and live independently HUMAN REPRODUCTIVE SYSTEM Primary Sex Organs - Also known as gonads - Unlike lungs, heart, or liver, and stomach, the gonads or primary sex organs depend on the sex of the individual  - Male gonad - testes - Female gonad - ovaries - The purpose of gonads is to secrete several different sex hormones and to produce sex cells called gametes - The gametes produces in males are sperm cells while the gametes produced in females are egg cells - When a sperm and an egg meet as a result of sexual intercourse, fertilization may occur Note: there are also Accessory reproductive organs (ducts/glands/external genitalia) MALE REPRODUCTIVE SYSTEM - The primary sex organ is the testes which is where testosterone is produced. It is housed in a sack of skin called the scrotum which is divided by a midline called the septum. Sperm is also produced here because the lower temperature is ideal. - Each testes is surrounded by the tunica albuginea followed by the tunica vaginalis - Inside, the testes is divided into lobules which contain coiled seminiferous tubules where the sperm is made from spermatogenic cells (through a process of spermatogenesis) - These tubules converge to form a straight tubule that lead to the rete testis - From here, sperm will move through a system of ducts, starting from the epididymis where they are stored until ejaculation. - When this happens, sperm cells move through the vas deferens, then to the ejaculatory duct, and eventually moving to the urethra just like urine - In doing so, it leaves the penis which is a copulatory organ which delivers sperm to the female reproductive tract. Together with the scrotum, they make up the external genitalia of a male. PARTS OF PENIS  - The penis contains three cylindrical shafts of erectile tissue, each covered by dense, fibrous, connective tissue. The erectile tissue is spongy (containing smooth muscle and vascular spaces) - When the vascular spaces fill up with blood during sexual arousal, the penis will enlarge and harden through a process called erection which enables penetration ACCESSORY GLANDS - The seminal gland, prostate, and bulbo-urethral gland - Seminal gland - sits on the surface of the bladder and produces a fluid called semen (semen does not contain sperm cells; but during ejaculation, sperm cells will mix into the semen in the ejaculatory duct. The semen will enhance sperm motility or fertilization abilities) - This is done through a mixture of hormones and other compounds that suppress the immune response in the female reproductive tract, destroy bacteria, and help sperm stick to wall of vagina and prevent drainage. - Semen makes most of the ejaculate by volume - The prostate - small gland that encircles the urethra near the bladder. Its purpose it to contract during ejaculation to allow prostatic secretion to enter the urethra and join the ejaculate, and activate the sperm - Bulbo-urethral gland - sit near the prostate and produces a mucus that lubricates the glans penis or head of the penis during arousal FEMALE REPRODUCTIVE SYSTEM - The female gonads are called ovaries where the female gametes are produced (egg cells or ova) as well as the sex hormones estrogen and progesterone) - There are accessory ducts which are the uterine tubes (fallopian tubes and the uterus) - There is also the vagina which leads to the the external genitalia OVARIES - Like testes but are inside the body - Surrounded by fibrous tunica albuginea, followed by a germinal epithelium, held in place by various ligaments and supplied by ovarian arteries - Ovary has outsize layer allied the cortex and an inner layer called the medulla - In the cortex, we see sacks called follicles, each of which houses an immature egg called an oocyte - The production of a mature egg cell is called oogenesis - When a primordial follicle matures, it becomes a vesicular follicle with a cavity called an antral. This follicle will then bulge out of the surface of the ovary, allowing it to eject the oocyte (this event is called ovulation) - This will then enter the uterine tubes or fallopian tubes which have sections called the isthmus, ampulla, and infundibulum (bears projections called fimbriae) - Fertilization will occur at some point along the fallopian tube which ends at the uterus (the womb). - This receives the fertilized egg, retains it in uterine wall and nourishes it to fetal development - Uterus has rounded top region call fundus and a narrow neck at the bottom called the cervix - Wall of uterus is quite thick, made up of three layers (perimetrium, myometrium (made up of smooth muscle), and endometrium (lines the uterine cavity or lumen) - Going through cervical canal, we reach the vagina which is the copulatory organ which receives the penis during intercourse EXTERNAL GENITALIA (COLLECTIVELY KNOWN AS VULVA) - Consist of the mons pubis, skinfolds that are calls labia majora and labia minora, clitoris, and vestibule - MAMMARY GLAND - Qualifying as part of the reproductive system are the mammary glands which are found in the breast (similar to sweat grands but start to produce milk during pregnancy before baby is born) - Each breast has a ring of pigmented skin called areola through which a nipple protrudes - Contains lobes separated by fibrous connective tissue and fat, which themselves contain smaller units called lobules which contains structures called alveoli which produces milk - The milk goes to lactiferous/milk duct which leads to a lactiferous sinus (where milk collects when mother is nursing)