CSET 119- Cell and Organismal Biology
7 multiple choice questions
1 constructed response
a. Describe organelles and explain their function in the cell
Organelles- tiny bodies in the cytoplasm.
Lysomes- special type of round vacuoles that contain powerful enzymes. Lysomes takes in bacteria and foreign bodies to be destroyed by the enzymes. Outer skin does not allow enzymes out into the cell, but if the cell is damaged, the n the skin disappears and the cell digests itself. Contains hydrolytic enzymes necessary for intracellular digestion. This is common in animals cells. Vacuoles act like this in animal cells.
Ribosomes- tiny round particles usually attached to the endoplasmic reticulum that are involved in the building of proteins from amino acids. “Coded” information is sent to the ribosomes in strands called the messenger RNA that pass on the codes so that ribosomes join the amino acids in the right way to make proteins. Ribosomes are also present as ribosomal RNA and molecules of transfer RUNA “carry” the amino acids to the ribosomes. Found in both plant and animal cells.
Endoplasmic Reticulum (ER)- flat sacs folding inward from cell membrane and joining up with nuclear membrane. It provides large surface area fro reaction or fluid storage, and a passageway for fluids passing through. ER with ribosomes is rough ER. ER without ribosomes is smooth ER. Found in plants and animals.
Golgi Apparatus- a special area of the smooth ER. It collects substances made in the cell. Once the sac fills up, it gets pinched off (vacuole) and travels out of the cells via cytoplasm. Found in plants and animals.
Centrioles- vital to cell division. In animals, they lie just outside the nucleus in the cytoplasm. They form an x-shape and is made up of nine sets of three tiny tubes. Found only in animal cells.
Nucleoli- one or two small round objects in the nucleus that produces the component parts of ribosomes which are carried out of the nucleus and assembled in the cytoplasm. They are then attached to the rough ER. Found in plants and animal cells.
Mitochondria- Commonly referred to as the Powerhouse. The mitochondria provides the cell energy it needs to produce secretory products. Inner layer of the folds that provides large surface area for vital chemical reaction which go inside the mitochondria. Places where simple substances taken into cell are broken down to provide energy. Found in plants and animals.
Plastids- these are tiny bodies in the plant cell's cytoplasm. Leucoplasts store starch, oil, or protein. Chloroplasts contain chlorophyll to make food (photosynthesis). Found in plant cells only.
Cytosol- the “soup” where organelles reside and metabolism occurs. Mostly water and full of proteins that control metabolism. Signals transduction, glycolyis, intercellular receptors, and transcription factors.
Peroxisomes- These are membrane-bound sacs filled with oxidative enzymes. In plant cells they play a variety of roles such as converting fatty acids into sugar and assisting chloroplasts with photosynthesis. Within the animal cells, peroxisomes protects the cells from the production of hydrogen peroxide. Hydrogen peroxide is produced to kill bacteria. Peroxisome enzymes then break down hydrogen peroxide into water and oxygen. Organelles found in both plants and animal cells.
b. Relate the structure of organelles and cells to their fuctions
Nucleus- enclosed in double membrane and communicates with surrounding cytosol. Here DNA is responsible for providing cell with unique characteristics.
Cell membrane- regulates tugor pressure in plants by collecting water and pressing outward agains cell wall and provides rigidity in the plant.
c. Identify and contrast animal and plant cells
Plastid- chlorophyll and leucoplasts
Vacuole-1 large permanent filled with cell sap (dissolved)
Small and temporary, remove substances from golgi complex or contains fluid brought in (pinocytosis)
Cell wall- provides structure and rigitiy, made out of cellulose which allows high pressure to build inside due to a plants need to accept large amounts of water through osmosis
No cell wall
Eukratic- defined nucleus
Eukratic- defined nucleus
Undergoes photosynthesis- has chloroplasts that has its own DNA
Tends to have regular shape
Shape tends to vary greatly in appearance
Lysosomes- is being debated, many say yes, some say they are rare
Has golgi apparatus
Has golgi apparatus
Centriole- in primitive plants only
Centrosome- simpler in plant cells, does not have centrioles
d. Explain the conversion, flow, and storage of energy of the cell
One example of energy conversion, flow and storage occurs during cellular respiration. Chemical bonds of the energy rich molecules, such as glucose, is converted into energy. Cells store energy, primarily within the chemical bonds found in fats, carbs ,and proteins. Fats store large amounts of energy which can be liberated by the breakdown of fat molecules stored within cells.
Aerobic respiration occurs when oxygen is present and acts as one of the driving elements driving the process of cell respiration forward.
Anaerobic respiration is the breakdown of molecules in the absence of oxygen to produce energy. Requires electron acceptors to replace oxygen.
e. Identify the function and explain the importance of mitosis and meiosis as processes of cellular and organismal reproduction
Mitosis- This is the process of cell division when a plant or animal cell divides for growth or repair. Mitosis ensures that the two new nuclei (daughter cells) have the same number or chromosomes called diploid number. Mitosis always has four stages and before mitosis begins, there is always an interphase.
Interphase- this is an active period, preparing materials to produce “copies” of all of it components. Chromatin threads in nucleus duplicates.
Stage 1: Prophase- the nuclear membrane disappear, chromatin thread coils up to form chromosomes. Each chromatin thread is joined by a centromere. The centrioles move to opposite poles of the cell.
Stage 2: Metaphase- The centrioles project protein fibers called spindle fibers which join together to form a sphere. Chromosomes move toward the equator and there centromeres becomes attached to spindle fibers.
Stage 3: Anaphase- centromere duplicate and the two daughter chromosomes move to opposite poles of the spindle.
Stage 4: Telephase- Spindle fibers and astral rays disappear and nuclear membrane forms again the daughter chromosomes.
Meiosis- this is the process of cell division when it divides to produce sex cells. Meiosis is split into two divisions: the first meiotic division (reduction division) and the second meiotic division. Meiosis ensures that each daughter cells have half the number or chromosomes called haploid number.
Meiosis Part 1:
Prophase 1: chromosomes become visible, chromosomes splits into chromatids, the chromatids then exchange segments (crossover), nucleus disappears, spindle forms, and nucleus envelope forms.
Metaphase 1: Spindle fibers from one pole of the cell attaches to one chromosome of each pair and the spindle fibers from opposite pole attach to the homologous chromosomes.
Anaphase 1: Begins when two chromosomes of each bivalent separate and start moving toward opposite poles of the cell as a result of the action of the spindle. There are 23 divided chromosomes on each side.
Telephase 1: homologous chromosome pairs reach the poles of the cell, nuclear envelope forms around them and cytokinesis follows to produce two daughter cells. Meiosis part 1 is completed.
Meiosis Part 2:
Prophase 2: nuclear envelop breaks down and the spindle apparatus forms, chromosomes become visible (no new chromosomes replication occurs before meiosis 2), centrioles duplicate.
Metaphase 2: single chromosomes align on the metaphase plate and the kinetochores of the sister chromatids face opposite poles and is attached to the kinetochore microtubule coming from that pole.
Anaphase 2: the centromeres separate and the two chromatids of each chromosome moves to opposite poles on the spindle.
Cytokinesis- cell divides again
Telephase 2: nuclear envelop forms and around each set of chromosome. The cells are now completely divided (four daughter cells each with a haploid set of chromosomes.) In males it' four sperm cells and in females 1 ova cell (the three ovas are reabsorbed into the parent's body), and in plats it is four spores.
f. Compare single-celled and multicellular organisms, noting the role of cell differentiation in the development of multicellular organisms
Organisms can be made up of a single or multiple cells. Most single-celled organisms are found in the Kingdom Monera and Protista. Most multi-celled organisms are found in the Kingdoms Fungi, Plantae, and Animalia.
Single-Celled organisms- these are tiny and microscopic. They may have a nucleus or chloroplast or other cell structures. They can be plant-like, animal-like, or bacteria-like. They reproduce either sexually or asexually. They live either alone or in colonies. Some are able to move around and some do not. They can get food from other organisms or make their own food. Single-celled organism were the first living organisms to develop on Earth approximately 3.5 billion years ago.
Multicellular organisms- They may have a nucleus, chloroplasts and mitochondria. They can be a plant, animal, or fungi. They reproduce either sexually or asexually. They live alone or in groups. Can more or cannot. Multicellular organisms evolved independently numerous of times. Beginning of the Cambrian Era, we saw a widespread arrival of multicellular organisms.
Multicellular life evolved from single cells in two stages. First, single-cells evolved the ability to form loose cooperative communities, called biofilms. Perhaps the earliest colony bacteria were the cyanobacteria that evolved more than 3 billion years ago (bya). Present day biofilms include slime, mold, dental plaque, films on rocks in streams, etc. perhaps 1 bya true multicellular organism formed, known as metazoans. Unlike cells in biofilms, all cells in a metazoan originally share the same DNA. As the orgnaisms develo9pes, the cells genetic programs direct them to permanently silence much of their DNA, thereby becoming specialized. Single=celled organisms function very well as individuals. However, some of that individuality had to be given up when cells combine together as one multicellular organism. For example in order to wok together as a coherent, multicellular body. Individual cells can't just dive into cell division otherwise, cancer forms.
Cell Specialization through Differentiation- Differentiation is intricately regulated by gene expressions which switches specific genes on and off at specific times. Differentiation can involved changes in numerous aspects of cell physiology (size, shape, activity, responsiveness, etc). There are different types of cells that go through differentiation:
Pluripotent Cells- these cells have the potential to develop into most types of specialized cells, not restricted to a specific system. For example, embryonic cells are pluripotent.
Totipotent Cells- these are cells that are able to regenerate into a whole new individual. For example, zygote and spore cells are totipotent.
Mutipotent Progentior Cells- these cells have the same basic features as stem cells. They differentiate into other different types of cells, but on into closely related family of cells. Blood stem cells are able to differentiate into different kinds of blood cells, but not into other cells, such as brain cells.
g. Describe the levels or organization (e.g., cells, tissues, organs, systems, organisms) in plants and animals.
In unicellular (single-celled) organisms, the single cell performs all of life functions independently. However, in multicellular (many-celled) organisms, they have various levels of organization with them. All plants and animals have five levels of organization for structure and function:
Level 1: Cells
These are the basic units of life. They carry out all of the vital chemical processes. For example, blood cells, nerve cells, bone cells, skin cells, etc.
Level 2: tissue
Groups of cells that are similar in structure and function form tissue. The cells work together to perform a specific activity. For example: nervous, bone, skin, etc.
There are four basic mammal types of tissue:
Connective- these protect and connect cells or organs and have the basis of non-living material in which living cells are scattered. Tissues found at the joint are all types of connective tissue and can either be tough (collegenn fibers) or elastic (elastic fibers)
There are various kinds of connective tissue:
Periosteum- these surrounds all bones, expert at the joints. They contain osteoblasts (cells with make new bone cells needed for growth and repair).
Ligaments- these are bands of connective tissue which holds together the bones of joints (and also many organs in place). Can be tough or elastic.
Synovial sac- this is a “bag” of lubricating fluid found at most movable joints
Tendons- these are bands of tough connective tissue joining muscles to bones.
Cartilage- these are tough connective tissue found in joints
Muscle- these are voluntary or involuntary. The muscle that contracts is called agonist (prime mover_ and the one that rests is called the antagonist. They contain specialize protein acting and myosin that slide past each other and allow movement. There are different kinds of muscle tissue:
1. skeletal- these muscles are attached to the bones of the skeleton. They are voluntary muscles made up of striated muscle tissue
2. cardiac- these muscles make up the wall of the heart. This is an involuntary muscle.
3. visceral- muscles in the walls of internal organs. They are involuntary, smooth muscles.
Nerve- this is the most complex tissue in the body and consists of two types of cells (neuron and glial). These tissues are found in the brain , spinal cord, and nerves. Nerve tissues require more oxygen and nutrients than any other body tissue
Epithelia- These are sheets of tightly packed together cells with forms a surface covering or a cavity lining throughout the body. They lies on top of connective tissue. For example, skin, inside of mouth, stomach.
There are three plant types of tissue:
Epidermis- forms outer surface of plants
Vascular- these tissues are involved in the transport of water and nutrients. They include the xylem and phloem.
Ground- these produce nutrients through photosynthesis and stores nutrients.
Level 3- Organs
Organs are made up of at least two tissues that work together to perform a specific activity. For example, heart, brain, skin, liver, kidney
Level 4- Organ System
An organ system consists of two or more organs working together to perform a specific function for the organism. There are 10 major organ systems in the body.
skeletal system- provides support for the body, protects internal organs, and provides attachment sites for organs
muscular system- provides movement
circulatory- transports nutrients, gases, hormones, and waste
neurones- relays electrical signal through the body. Working with the endocrine system, they control physiological processes such as digestion, circulation, etc.
Respiratory- provides gas exchange between blood and the environment.
Digestive- breaks down and absorbs nutrients
Excretory system- filers out cellular waste, toxins, and excess water or nutrients from the circulatory system.
Endocrine- relays chemical messages through the body and helps control physiological process such as nutrient absorption and growth.
Reproductive system- manufactures cells that allows reproduction
Lymphatic/Immune system- destroys and removes invading microbes and viruses from the body. Also removes fat and excess fluids from the blood.
Level 5- Organism
Entire living things that can carry out all basic life process: take in materials, release energy from food, release wast, grow, respond to the environment, and reproduce. Usually made up of an organ system, but may be made up of only one cell such as bacteria or protist.
h. Describe the structures and functions of human body systems, including, but not limited to, the skeletal, reproductive, nervous, and circulatory systems.
This is a system of blood vessels (arteries, veins, and capillaries). Endothelium is a tissue that lines the arteries and veins and is the only layer of the capillary. The pumping of the heart, the muscles within the veins/arteries, and the pressure all help blood to flow through the body.
Major organs include:
- Blood Vessels:
Arteries- carry blood away from the heart. Arteries consist of a wide, thick walled blood vessel. As it moves away from the heart, they begin to branch out.
Capillaries- these are small, thin walled vessels that branch off from arteries. They pass oxygen and dissolved food through their thin walls into the body cells while carbon dioxide and waste is passed in. The capillaries of the digestive organs and liver also pick up food. Capillaries then join up to form venules.
Except for the pulmonary artery, arteries and capillaries carry fresh oxygen, dissolved nutrients, and waste that was transferred by the veins in the heart. Arteries and capillaries transfer food to the cells. Wasts is carried to the kidneys.
Veins- these are wide, thick walled vessels that carry blood back to the heart. They have valves that prevent blood from flowing back due to gravity. Veins are formed from merging venules. Venuels are formed from merging capillaries.
2) Heart- a muscle that pumps the blood
3) Blood- plasma, blood cells (red, white, platelets)
Pulmonary Circulation- this is the movement of blood from the heart into the lungs, and lungs into the heart. When the veins enter the right atrium and bring in wast-rich, oxygen depleted blood in the lungs, the right atrium fills with waste-rich blood. It contracts and pushes the blood through a one way valve into the right ventricle. The right ventricle then contracts and pushes the blood into the pulmonary artery which leads into the lungs. In the lung capillaries oxygen replaces carbon dioxide. The fresh blood moves into the pulmonary veins and returns to the heart by entering through the left atrium. It passes through a one way valve into the left ventricle and exit the heart through the aorta where it will continue through the arteries.
Coronary Circulation- The heart itself is an organ that requires fresh oxygen and nutrients in order to work. Coronary circulation refers to the movement of blood through the tissues of the heart.
Central Nervous System:
The CNS coordinates all mechanical and chemical actions, working with hormones. CNS is made up of the brain and spinal cord. There are millions of nerves in the body that carry “massages” to and from the central areas of the CNS.
Brain- only organ able to produce “intelligent” actions and is made up of millions of neurons that are arranged into sensory associations and motor areas. Sensory associations received info from all parts of the body and analyzes the impulses and makes decisions. Motor areas sends impulse to muscles or glands. The impulses are carried by the fibers of 43 pairs of nerves, 12 pairs of cranial nerves serving the head and 31 pairs of spinal nerves.
Spinal Cord- is a long string of nervous tissue running down from the brain inside the vertebral column. Nervous impulses from all parts of the body pass through it. Each spinal cord is made up of two groups of fibers: a dorsal, or sensory root, bringing impulses in and a ventral, or motor root, taking impulses out.
Neuralgia (glia)- stiffened cells which support and protect the nerve cells, some produce myelin that coats the long fibers found in the connective layer of the spinal cord and leads to areas known as white matter. Grey matter consists mainly of cell bodies and their short fibers. It's neuralgia do not produce myelin.
Provides: shape and form for our bodies, supports and protects the internal organs, allows body movement (along with the muscular and skeletal system), produces blood, stores mineral (such as calcium). Muscles are connected to bones by tendons. Bones are connected to each other by ligaments. Bones meet at many joints. Some are fixed joints and allows no movement. Blood cells are produced by the marrow located in some bones.
Process of producing new life.
Male Reproductive System- the testes contain tube-like canals (seminiferous tuble) where sperm (gametes, sex cells) are produced after puberty. The testes lie in a sac (scrotum) which hangs below the abdomen because sperm production needs a slightly lower temperature than the body temperature. Sperm is ejected through the organ, penis.
Female Reproductive System- the ovaries are held in place by ligaments and are attached to the wall of the pelvis. The female gametes is called ova and are produced after puberty. The vulva is a collective term for the outside parts: labia, clitoris (erective tissue and has receptors). Ovarian follicles are area of tissue in the ovaries after puberty. The follicles get larger and secrete hormones (estrogen). The uterus is the hollow organ where a fetus may be held or from which the ova is discharged. It has a mucous membrane covering the muscular wall with many blood vessels. Vagina is the muscular canal leading from the uterus out of the body. It came away the ova and endometrium during menstruation.
Important in recycling body fluid and fighting against disease. Organs consist of lymph, lymph nodes, vessels, white blood cells, T- and B- cells. This system works with the circulatory system. The food and oxygen carried by the vessels do not actually tough the cells. A fluid surrounds the body cells, called intercellular fluid, and seeps out through the capillary wall. It carries oxygen and dissolved food to the body cells and carbon dioxide and wast away from them. Protein molecules and waste too large to re-enter the capillaries pass into the lymph capillaries. The liquid in lymph vessels is called lymph and contains lymphocytes, some substances picked up from tissue fluid and fat particles. Lymph vessels are tubes that carry lymph from all area of the body up to the neck where it is empties back into the blood. The lymph vessels are lined with endothelium and have valves that stop the lymph from going back due to gravity. The lymph capillaries pick up fat particles that are too big to enter the bloodstream directly. These capillaries join to form lymphatics which finally unite to form the right lymphatic duct and the thoracic duct. This system works with the sleep organ, where it holds onto an emergency store of red blood cells, contains some white blood cells (fixed macrophage) and destroys foreign bodies. Thymus gland found in the upper part of the chest that eventually undergoes atrogphy.
Major organs include mouth, esophagus, stomach, small and large intestines. Food ingested n passed through the digestive system. It is gradually broken down into simple soluble substances that are absorbed into the blood vessels and transported to the body cells.
Alimentary canal/gastrointestinal tract- is a collective term for all the parts of the digestive system. The GT is a long tub running from the mouth to the anus. They are held in place by mesentines. Pharynx is the cavity at the back of the mouth where the mouth and the nasal cavity meet. When food is swallowed, a soft tissue flap closes the nasal cavity and the epiglottis closes the trachea. Esophagus is a tube that food travels through to the stomach. A piece of swallowed food is called a bolus. Cardiac sphincter is a muscular ring between the esophagus and stomach that relaxes to open and let food through. Stomach is a large sac. Its lining has folds that flatten out to let it expand. Some substances pass through the wall of the stomach into the blood vessel while the semi-digested food moves into the small intestine. Intestine It relaxes to let food through after certain digestive changes have occurred. Small intestine is a coiled tube that has three parts: duodenum (main area of digestion), jejunum, and ilium. Villus project upward from it's lining with each containing capillaries into which most of the food is absorbed and a lymph vessel (lacteal) which absorbs recombined fat particles .The remaining semi liquid waste mixture passes on into the large intestine. This has a thick tube that receives wast from the small intestine. It consist of the cecum (redundant sac), colon, rectum, and anal canal. The L.I. Contains bacteria that breaks food down and makes vitamins. Most water passes through the colon walls into nearby blood vessels, which leaves semi-solid mass (feces) pushed out via the rectum, anal canal, and anus (hole surrounded by a muscular ring anal sphincter). Mucous membrane is a thin layer of tissue lining all digestive passages. Special type of epithelium that contains many single-celled exocrine glands (mucous glands). These secrete mucous, a lubricating fluid, that protects the walls against the digestive juices. Peristalis is a wave of contraction produced by muscles in the walls of organs that moves substances along.
This system produces the hormones directly in the blood (ductless glands). The major organs involved:
Pituitary gland- this gland releases tropic hormones which regulates the activity of the other endocrine glands.
Adrenal glands- located close to the kidneys, this gland is responsible for releasing adrenaline.
Pancreas- produces/releases insulin and glucagon
Ovaries- produces progesterone, estrogen, and eggs
Testes- produces testosterone and sperm
Thymus Gland- this gland is essential in the development of the immune system
Immune System- this system's role is to defend the body from disease-causing agents, such as bacteria. Major organs include:
White Blood Cells- cells that are produced in the bone marrow and defends the body against infectious and foreign bodies
Lymph Nodes- contain colorless fluid (lumph) that circulates through the vessels of the lymphatic system
This system produces voluntary and involuntary movements to the body. There are three types of muscles in the body:
Skeletal muscles- these are attached to the bones of the skeleton. Voluntary muscles are made up of striated muscle tissues
Cardiac muscles- involuntary muscles that forms the contractile walls of the heart
Visceral muscles- involuntary muscles found along the walls of the internal organs
Exchanges of oxygen and carbon dioxide takes place in this system. Major organs include:
Lungs- contains air-fluid sacs called alveoli
Bronchi- tubes leading from trachea to lungs
Pharynx- connects mouth to trachea and esophagus
Epiglottis- flap of tissue that prevents food and water from passing into the trachea
Trachea- cartilaginous and membranous tube that carries air between the bronchi and pharynx
Responsible for removal of liquid waste. It also regulates water and pH. Organs include:
Kidneys- comprised of a million microscopic nephrons. Responsible for filtering liquid waste from the blood
Uterus- pair of tubes leading from kidney to the bladder
Urinary bladder- muscular sack that stores urine
Urethra- tube leading from bladder to the outside of the body
i. Explain the major structures and their functions in vascular and nonvascular plants
These types of plants have a complex system of special flue-carrying tissue called vascular tissue. This tissue runs throughout the vascular plant and help to carry fluid and provides support. In young stems, it is arranged in separate units called vascular bundles and in older stems, they are joined up and are called vascular cylinder. There are two types of vascular tissue: xylem and phloem. There is a layer of tissue that separates them called cambium.
Xylem Tissue- these tissues carry water up through the plant. The way I remember this is that the letter x is right next to the letter w (xylem=water). It is made up of vessels with long, thin fibers that provides support between them. As the xylem ages, it begins to fill in. It does not transport water anymore, but still provides structure.
Cambium- is a layer of narrow, thin-walled cells found between the xylem and phloem. These cells are bale to divide and create more xylem and phloem. This region is called a meristem.
Phloem Tissue- these tissues transports and distributes the food made in the leaves to other parts of a plant. There are sieve tubes with special fluid-carrying companion cells beside them along with other cells packed around for support.
Epidermis- this is a thin layer of tissue around the parts of a plant. In the leaves are tiny holes (stomata). In older plants, it is replaced by phellem.
Cortex- is a layer or tissues inside the epidermis of stem and roots. Consists of a tissue with large cells and air spaces (parenchyma). There is also a tissue with long, thick-walled cells (collenchyma). As it ages, the cortex tends to get compressed and replaced by other tissue.
Endodermis- is the inner most layer of root cortex.
Pith- this is the central area of tissue foun in stems.
Cuticle- this is a thin layer of waxy substance (cutin) made by the epidermis. This prevents too much water from being lost.
These types of plants have no vascular system. They do not have roots, stems, or leaves. There are no phloem or xylem tissues to carry water and nutrients through the plant. Instead, many non-vascular plants posses tissues specialized for the transport of water to parts of the plant. Two groups of non-vascular plants are the bryophyta (mosses and liverworts, and hornworts) and algae. The lack of vascular tissue means that most non-vascular plants reside in moist habitats.
j. Describe the life processes of various plant groups, including, but not limited to, reproductive, photosynthesis, respiration, and transpiration.
Photosynthesis- described in Molecular and Biology letter e.
Respiration and Transpiration- described in Molecular and Biology letter d
Flowering Plants- The organs for reproduction are located in the flowering part of a plant. There are three main types of flowering plants:
Hermaphrodite Plants- these plants contain both male and female reproductive organs.
Monoecious Plants- these plants have two types of flowers on one plant: staminate flower (has just male organs) and pistillate flowers (which has just female organs).
Dioecious Plants- these plants have staminate flower on one plant and pistillate flowers on a separate plant.
Pistil- consists of an ovary, stigma, and style
Ovaries- each is the main part of the pistil and contains tiny bodies called ovules (contains a female sex cell). An ovule is fixed by a stalk (funicle) to the ovaries placenta. The stalk is attached to the ovule at a point called a chalaza.
Stigma- the sticky upper part of a pistil that collects grain of pollen (pollination)
Style-part of the pistil that connects the stigma to the ovary.
Gynoecium- the whole reproductive structure that is mad up of one or more pistils.
Female gamete becomes a seed after fertilization (by the pollen). Consists of an oval cell surrounded by tissues called integuments. Before fertilization, the embryo sac nucleus undergoes division which results in new cells and two naked nuclei fused together. One of the new cells is the female gamete.
Stamen- this is the male reproductive organ that consists of a think stalk (filament) with an anther at the tip. The anthers are made up of pollen sacs filled iwth pollen (male gametes).
Androecium- collective term for all male parts of a flower
Pollen- formed by the stamen. Each pollen is a special cell with two nuclei. When a pollen grain lands on an ovary, one nucleus (generative nucleus) divides into two forming two male nuclei. That other into a pollen turb during pollination. When pollination occurs, a grain of pollen transfers its male nuclei into the ovary. The grain lands on the sticky surface of the stigma where it then forms a pollen tube. This tube travels down through the ovary tissue and enters an ovule through the micropyle (tiny hole in the integument tissue). The two male nuclei then travels down this path. The one male nucleus fuses with the egg cell in the ovule to form a zygote (fertilization). The other male nucleus joins with the two fused female nuclei to form a cell which develops into the endosperm.
Cross-Pollination- this is the pollination of one by plant by pollen grains from another plant.
Self-Pollination- the pollination of a plan by its own pollen grains.
Vegetative Reproduction- this is a type of asexual reproduction without spores or seeds.
Bulbs, corn, rhizome, stolen/runner, tuber are all kinds of vegetative reproduction.
k. Explain the reproductive processes in flowering plants
Pollen grains contain the male gametes. Pollen grains are produced through the process of meiosis by the microspore mother cells, which is located along inner edge of the anther sacs. The outer part of the pollen is the exine (composed of polysaccaride, sporopollenin). Inside the pollen are two to three cells that comprise of the male gamete. The tube cell (or tube nucleus) develops into pollen tube. The germ cells divide by mitosis to produce 2 sperm cells. Division of the germ cells can be before or after pollination.
Pollination- this is the transfer of pollen from the male anther to the female stigma. Can be transferred in a number of ways:
by entomophyly (insects)
or some plants have methods to ensure self-pollination
Once pollination has been achieved, the pollen tube grows through the stigma and into the style, heading towards the ovary. The germ cells in the pollen divides and releases two sperm cells which now move down the pollen tub. The tube grows through the micropyle and into the embryo sac. One sperm fuses with the egg producing a zygote. The second sperm fuses with the two polar bodies in center of the sac, producing an endosperm tissue (provides energy for the embryo's growth and development).
The ovary wall will then develop into a fruit.