Unit 1: Organismal Biology PDF

Joven A. Pedrera, LPT, MSc. & Jonah Jean R. Callao, MSc. General Biology 2 Instructors ▪ A. Compare and contrast the following processes in plants and animals: reproduction, development, nutrition, gas exchange, transport/circulation, regulation of body fluids, chemical and nervou...

Joven A. Pedrera, LPT, MSc. & Jonah Jean R. Callao, MSc. General Biology 2 Instructors ▪ A. Compare and contrast the following processes in plants and animals: reproduction, development, nutrition, gas exchange, transport/circulation, regulation of body fluids, chemical and nervous control, immune systems, and sensory and motor mechanisms. ▪ B. Explain how some organisms maintain steady internal conditions that possess various structures and processes. ▪ C. Describe examples of homeostasis (e.g., temperature regulation, osmotic balance and glucose levels) and the major features of feedback loops that produce such homeostasis. ▪ Most organisms’ do not all look and act the same because different types of organisms have different structures that enable them to function in particular ways. ▪ All organisms have structures that carry out functions the organism needs to survive and reproduce. ▪ However, organisms carry out their life functions differently depending on how many cells they have. A single- celled organism has only one cell, its one cell performs all the life functions of the organism. In contrast, a multicellular organism has many cells. Each cell does not perform every life function on its own. Instead, the cells work together to carry out the life functions of the organism. ▪ All living things are systems. As such, they are made of related parts that work together to help them function. ▪ Like many systems, a multicellular organism is ordered. Its part are ordered, or organized, into levels from simple to complex. ▪ The simplest level is the cell. In multicellular organisms, cells are specialized, or differentiated, to perform certain jobs. ▪ Because they carry out particular functions, differentiated cells can look very different from one another. ▪ Each cells perform different functions. “Neurons, receiving sensory input from the “carry oxygen from “Collenchyma cells are elongated external world, for sending motor commands to our lungs to the rest and provide support to growing plant our muscles, and for transforming and relaying of our bodies" organs, like leaves” the electrical signals at every step in between” ▪ A group of differentiated cells forms a tissue. A tissue is a group of similar cells that work together to do a particular job. ▪ For example, most animals have muscle tissues, which are made up of muscle cells. In animals such as humans, muscles cells in some muscle tissues work together to move bones. ▪ Within a multicellular organism, different types of tissues can form an organ. The stomach, an organ that digest food, is made up of different tissues. Muscle tissue in the stomach helps move food through the organ. Epithelial tissue in the inner lining of the stomach secrets fluids that aid in digestion. ▪ In plants and animals, organs can form organ systems. The human digestive system includes organs such as stomach, intestines, gallbladder, and pancreas. These organs work together to breakdown food into small molecules the body can use. ▪ This system consists of the bones and the muscles. The bones form the skeleton which is the framework within the body. It carries weight and supports the body. ▪ Bones are connected together so they can move. The places where this happens are called joints. The bones are held together at the joints by elastic strands called ligaments. Between the bones is a softer material called cartilage (gristle) which cushions the bones at the joints when the body moves. Bones are very hard and contain minerals. Each bone has a name such as the scapula (shoulder blade) and skull (head). There are about 206 bones in an adult human body and 300 for babies at birth. ▪ Muscles are joined at both ends to the bones. The muscles are the meat of the body and when they contract (shorten) or relax (lengthen) they make the bones move. ▪ If you bend your arm you can see and feel the muscles in your arm working. Simplified diagram of Muscular and Skeletal System ▪ The digestive system consists of the teeth, mouth, gullet (esophagus), stomach, liver, intestine, pancreas, and rectum. ▪ Digestion begins in the mouth where feed is broken down into small pieces by the teeth and mixed with saliva before being swallowed (“Bolus”). ▪ In the stomach feed is mixed with the juices to form a soft paste (“Chyme”). This then passes into the intestine where bile from the liver and juices from the pancreas are added. ▪ The action of these juices is to break down the feed and allow the nourishment it contains to be absorbed by the blood in the walls of the intestine. Waste matter collects in the rectum and passes out of the body through the anus (or cloaca in birds). ▪ Gastric juices – digestive enzymes (HCL, pepsin, lipase, mucin) 2 Types of Digestion 1. Mechanical Digestion - involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion. 2. Chemical Digestion - further degrade the molecular structure of the ingested compounds by digestive enzymes into a form that is absorbable into the bloodstream. ▪ The organs of the circulatory system are the heart and the blood vessels (tubes). The heart is found in the chest cavity. It is a muscular pump which sends blood around the body. ▪ The blood vessels which carry blood away from the heart are called arteries. Blood returns to the heart in veins. Joining the arteries and veins is a fine network of small tubes called capillaries. The capillaries pass through every part of the body. ▪ When the heart beats its muscles contract and sends blood out through the arteries. When the heart relaxes blood flows into it from the veins. ▪ Every time the heart beats it sends a pulse along the arteries. You can feel it at certain points on the body. By feeling the pulse we can count the rate at which the heart beats. You can feel your pulse on your wrist. TWO TYPES OF CIRCULATION: PULMONARY CIRCULATION AND SYSTEMIC CIRCULATION ▪ PULMONARY CIRCULATION moves blood between the heart and the lungs. It transports deoxygenated blood to the lungs to absorb oxygen and release carbon dioxide. The oxygenated blood then flows back to the heart. ▪ SYSTEMIC CIRCULATION moves blood between the heart and the rest of the body. It sends oxygenated blood out to cells and returns deoxygenated blood to the heart. ▪ Respiration (breathing) consists of inspiration (breathing in) and expiration (breathing out). ▪ There are two lungs which are found in the chest protected by the bony cage of the ribs. The windpipe carries air from the nostrils to the lungs which are spongy because of air spaces in them. ▪ As the animal breathes, air moves in and out of the lungs. Inside the lungs oxygen needed by the body passes into the blood in the walls of the lungs and water and carbon dioxide pass out of the blood into the air which is then breathed out. ▪ The kidney and urinary systems help the body to get rid of liquid waste called urea. They also help to keep chemicals (such as potassium and sodium) and water in balance. Urea is produced when foods containing protein (such as meat, poultry, and certain vegetables) are broken down in the body. Urea is carried in the blood to the kidneys. This is where it is removed, along with water and other wastes in the form of urine. ▪ The kidneys have other important functions. They control blood pressure and produce the hormone erythropoietin. This hormone controls red blood cell production in the bone marrow. The kidneys also control the acid-base balance and conserve fluids. ▪ The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries (glomerulus) and a small tube called a renal tubule. ▪ Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney. ▪ NERVOUS SYSTEM is divided in two components: Central Nervous System (CNS) consist the brain and spinal cord, and Peripheral Nervous System (PNS), which encompasses nerves outside the brain and spinal cord. These two components cooperate at all times to ensure our lively functions: we are nothing without our nervous system! ▪ Unlike the brain and the spinal cord of the central nervous system that are protected by the vertebrae and the skull, the nerves and cells of the peripheral nervous system are not enclosed by bones, and therefore are more susceptible to trauma. ▪ If we consider the entire nervous system as an electric grid, the central nervous system would represent the powerhouse, whereas the peripheral nervous system would represent long cables that connect the powerhouse to the outlying cities (limbs, glands and organs) to bring them electricity and send information back about their status. ▪ THE REPRODUCTIVE SYSTEM is a collection of internal and external organs — in both males and females — that work together for the purpose of procreating. ▪ Due to its vital role in the survival of the species, many scientists argue that the reproductive system is among the most important systems in the entire body. ▪ THE MALE REPRODUCTIVE SYSTEM consists of two major parts: The Testes, where sperm are produced, and The Penis. ▪ The penis and urethra belong to both the urinary and reproductive systems in males. ▪ The testes are carried in an external pouch known as the SCROTUM, where they normally remain slightly cooler than body temperature to facilitate sperm production. ▪ The External Structures of the Female Reproductive System include the clitoris, labia minora, labia majora and Bartholin's glands. The major Internal Organs of the Female Reproductive System include the vagina and uterus — which act as the receptacle for semen — and the ovaries, which produce the female's ova. ▪ The vagina is attached to the uterus through the cervix, while the fallopian tubes connect the uterus to the ovaries. In response to hormonal changes, one ovum, or egg — or more in the case of multiple births — is released and sent down the fallopian tube during ovulation. If not fertilized, this egg is eliminated during menstruation. ▪ Fertilization occurs if a sperm enters the fallopian tube and burrows into the egg. While the fertilization usually occurs in the oviducts, it can also happen in the uterus itself. ▪ The egg then becomes implanted in the lining of the uterus, where it begins the processes of embryogenesis (in which the embryo forms) and morphogenesis (in which the fetus begins to take shape). ▪ When the fetus is mature enough to survive outside of the womb, the cervix dilates, and contractions of the uterus propel it through the birth canal. ▪ Lymph is a colorless fluid which passes out of the blood into a network of fine tubes called the lymphatic system. ▪ It passes through the lymph nodes, where germs are filtered out and killed, before it is returned to the veins. ▪ The lymph nodes and spleen also produce special blood cells which protect the body against disease. ▪ Sometimes when an animal is infected the lymph nodes become swollen and can be felt beneath the skin. ▪ Maintains fluid levels in your body: As just described, the lymphatic system collects excess fluid that drains from cells and tissue throughout your body and returns it to your bloodstream, which is then recirculated through your body. ▪ Absorbs fats from the digestive tract: Lymph includes fluids from your intestines that contain fats and proteins and transports it back to your bloodstream. ▪ Protects your body against foreign invaders: The lymphatic system is part of the immune system. It produces and releases lymphocytes (white blood cells) and other immune cells that monitor and then destroy the foreign invaders — such as bacteria, viruses, parasites and fungi — that may enter your body. ▪ Transports and removes waste products and abnormal cells from the lymph. ▪ THE INTEGUMENTARY SYSTEM is the largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain. ▪ The integumentary system includes ▪ Skin (epidermis, dermis) ▪ Hypodermis ▪ Associated glands ▪ Hair ▪ Nails. ▪ In addition to its barrier function, this system performs many intricate functions such as body temperature regulation, cell fluid maintenance, synthesis of Vitamin D, and detection of stimuli. ▪ The various components of this system work in conjunction to carry out these functions ▪ Endocrine systems, also referred to as hormone systems, are found in all mammals, birds, fish, and many other types of living organisms. They are made up of: ▪ Glands located throughout the body; ▪ Hormones that are made by the glands and released into the bloodstream or the fluid surrounding cells; and ▪ Receptors in various organs and tissues that recognize and respond to the hormones. ▪ Hormones act as chemical messengers that are released into the blood stream to act on an organ in another part of the body. Although hormones reach all parts of the body, only target cells with compatible receptors are equipped to respond. Over 50 hormones have been identified in humans and other vertebrates. ▪ Hormones control or regulate many biological processes and are often produced in exceptionally low amounts within the body. Examples of such processes include: ▪ blood sugar control (insulin); ▪ differentiation, growth, and function of reproductive organs (testosterone (T) and estradiol); and ▪ body growth and energy production (growth hormone and thyroid hormone). Some examples of hormones include: ▪ Estrogens are the group of hormones responsible for female sexual development. They are produced primarily by the ovaries and in small amounts by the adrenal glands. ▪ Androgens are responsible for male sex characteristics. Testosterone, the sex hormone produced by the testicles, is an androgen. ▪ The thyroid gland secretes two main hormones, thyroxine and triiodothyronine, into the bloodstream. These thyroid hormones stimulate all the cells in the body and control biological processes such as growth, reproduction, development, and metabolism. ▪ THE ENDOCRINE SYSTEM, made up of all the body's different hormones, regulates all biological processes in the body from conception through adulthood and into old age, including the development of the brain and nervous system, the growth and function of the reproductive system, as well as the metabolism and blood sugar levels. ▪ The female ovaries, male testes, and pituitary, thyroid, and adrenal glands are major constituents of the endocrine system. Instructions: Complete the table below by listing five (5) organ system that we discussed earlier. Name of the System Organ of the system Functions Ex. Circulatory System Heart and Blood vessels Carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide 1. 2. 3. 4. 5 ▪ Plants are as essential to human existence as land, water, and air. ▪ Without plants, our day-to-day lives would be impossible because without oxygen from photosynthesis, aerobic life cannot be sustained. ▪ From providing food and shelter to serving as a source of medicines, oils, perfumes, and industrial products, plants provide humans with numerous valuable resources. ▪ When you think of plants, most of the organisms that come to mind are vascular plants. These plants have tissues that conduct food and water, and they have seeds. Seed plants are divided into gymnosperms and angiosperms. ▪ Gymnosperms include the needle-leaved conifers—spruce, fir, and pine—as well as less familiar plants, such as ginkgos and cycads. Their seeds are not enclosed by a fleshy fruit. ▪ Angiosperms, also called flowering plants, constitute the majority of seed plants. They include broadleaved trees (such as maple, oak, and elm), vegetables (such as potatoes, lettuce, and carrots), grasses, and plants known for the beauty of their flowers (roses, irises, and daffodils, for example). ▪ While individual plant species are unique, all share a common structure: a plant body consisting of stems, roots, and leaves. They all transport water, minerals, and sugars produced through photosynthesis through the plant body in a similar manner. ▪ All plant species also respond to environmental factors, such as light, gravity, competition, temperature, and predation. ▪ In plants, just as in animals, similar cells working together form a tissue. When different types of tissues work together to perform a unique function, they form an organ; organs working together form organ systems. ▪ Vascular plants have two distinct organ systems: a shoot system and a root system. The shoot system consists of two portions: the vegetative (non- reproductive) parts of the plant, such as the leaves and the stems; and the reproductive parts of the plant, which include flowers and fruits. ▪ The shoot system generally grows above ground, where it absorbs the light needed for photosynthesis. ▪ The root system, which supports the plants and absorbs water and minerals, is usually underground. ▪ The Shoot Organ System in a plant is made from leaves, stems, buds, fruits and flowers. Functions: ▪ Photosynthesis ▪ Support ▪ Transport substances ▪ Produce flowers for sexual reproduction ▪ The Root Organ System of most plants are all the parts that are underground. Functions: ▪ Anchorage ▪ Absorb water and minerals from soil ▪ Store food ▪ A plant’s health is very closely tied to its roots. When roots are weak or diseased, the whole plant has difficulties. ▪ The roots need to be constantly growing in order to stay healthy. ▪ The root system serves some important functions. ▪ The roots absorb water and minerals that a plant needs to live. ▪ The roots anchor the plant to the ground and support the above ground part of the plant. ▪ The roots store food that has been made through photosynthesis. This food can be used later when a plant needs it to grow or survive. ▪ When a plant seed germinates, the first structure to emerge from the seed is a root. This root, initiated by a germinating seed, is called a seminal root. ▪ The seminal root becomes the primary root and, on some plants, it is the most important root in the whole root system. ▪ Other roots eventually branch out from the primary root. These are called secondary or lateral roots. At the tip of the root, there is an area where new cells develop, called the apical meristem. ▪ The apical meristem is easily damaged, and so it has a root cap over the top of it to protect it from damage as it grows through the large, and sometimes coarse, soil particles. ▪ The surface of the root is covered with a skin of cells called the epidermis. ▪ The epidermis is where the water and minerals enter the root through osmosis and diffusion. The epidermis generates distinctive growths, or hairs, called trichomes. ▪ The most common type of trichome is the root hair. Root hairs greatly increase the surface area of the root, and thereby improve the absorption of water and minerals. ▪ Root hairs are located about 1/2 inch from the root cap. Each root hair is an individual cell. Root hairs live for only a few days and never develop into multi-cell roots. Because of their short life, roots need to grow continually. ▪ Epidermis. The outermost tissue of the root. It is usually a single layer. In the root elongation zone are root hairs, which are active in water and mineral nutrient uptake. ▪ Cortex. Cortex tissue is made up of parenchyma cells. ▪ The primary function of the cortex is the storage of starches. Some examples of roots with tremendous starch storage capability are sweet potatoes, yams, turnips, carrots, and sugar beets. ▪ Endodermis. The innermost layer of cortex that encircles the vascular tissue. ▪ It blocks absorbed soil water from passing between the cells to the xylem; thus, water and mineral nutrients must pass through the selectively permeable membranes of endodermis cells instead, an effective filtering system. ▪ Pericycle. The central cylinder of vascular tissue is surrounded by thin-walled parenchyma tissue called pericycle. ▪ The pericycle is the site where vascular cambium and lateral roots originate. As a lateral root penetrates through the cortex, its apical meristem and its derivative tissue systems become organized. ▪ The pericycle is also involved in the secondary (woody) growth of woody plant roots. Which do you think is the taproot? How about fibrous root? ▪ Plant root systems are organized in two basic ways. The two ways have much to do with primary and secondary roots. ▪ A root system that is composed of one main primary root and many secondary roots branching off the primary root is called a taproot system. Many dicot plants have taproot systems. ▪ A type of taproot highly specialized for the storage of starches is called a napiform root. Examples of napiform roots include radishes, beets, turnips, and carrots. ▪ A system that has no dominant primary root but is made of many primary and secondary roots of similar size is called a fibrous root system. ▪ Monocot plants typically have fibrous root systems. ▪ Some plants readily produce roots along their stems or at nodes of stems. ▪ These roots, which arise from a stem, are referred to as adventitious roots. ▪ The shoot system consists stems, leaves, and the reproductive parts of the plant (flowers and fruits). ▪ The shoot system generally grows above ground, where it absorbs the light needed for photosynthesis. ▪ Stems are a part of the shoot system of a plant. ▪ Their main function is to provide support to the plant, holding leaves, flowers and buds. Connect the roots to the leaves, transporting absorbed water and minerals from the roots to the rest of the plant, and transporting sugars from the leaves (the site of photosynthesis) to desired locations throughout the plant. ▪ They may range in length from a few millimeters to hundreds of meters, and also vary in diameter, depending on the plant type. Stems are usually above ground, although the stems of some plants, such as the potato, also grow underground. Stems can be of several different varieties: C. A. Herbaceous stems are soft and typically green Woody stems are hard and wooded Unbranched stems have a single stem Branched stems have divisions and side stems B. ▪ Plant stems, whether above or below ground, are characterized by the presence of nodes and internodes. ▪ Nodes are points of attachment for leaves and flowers; internodes are the regions of stem between two nodes. ▪ The tip of the shoot contains the apical meristem within the apical bud. ▪ An axillary bud is usually found in the area between the base of a leaf and the stem where it can give rise to a branch or a flower. ▪ The stem and other plant organs arise from the ground tissue, and are primarily made up of simple tissues formed from three types of cells: parenchyma, collenchyma, and sclerenchyma cells. ▪ Parenchyma cells are the most common plant cells. They are found in the stem, the root, the inside of the leaf, and the pulp of the fruit. Parenchyma cells are responsible for metabolic functions, such as photosynthesis, and they help repair and heal wounds. Some parenchyma cells also store starch. ▪ Collenchyma cells are elongated cells with unevenly thickened walls. ▪ They provide structural support, mainly to the stem and leaves. ▪ These cells are alive at maturity and are usually found below the epidermis. ▪ The “strings” of a celery stalk are an example of collenchyma cells. ▪ Sclerenchyma cells also provide support to the plant, but unlike collenchyma cells, many of them are dead at maturity. ▪ There are two types of sclerenchyma cells: fibers and sclereids. ▪ Fibers are long, slender cells; sclereids are smaller-sized. Sclereids give pears their gritty texture. Humans use sclerenchyma fibers to make linen and rope. ▪ Modified stems can be categorized into three types: 1. Underground – Rhizome, Bulb, Corm, Tuber 2. Subaerial – Runner, Sucker, Offsets, Stolon 3. Aerial – Tendrils, Thorn, Bulbils, Cladode, Phylloclade 1. Underground. These are present underground. They serve various purposes such as storage of food, propagation and perennation. They can be identified from roots by the presence of nodes and internodes. They help in propagation through asexual reproduction and help the plant survive a period of dormancy. They provide protection from grazing by animals and environmental stress. Rhizome – It runs parallel to the ground, the upper portion can produce scaly leaves and the bottom portion can give rise to adventitious roots. They contain, nodes, internodes and buds. Ex. Examples: Ginger, turmeric. Banana contains rootstock, which is rhizome growing vertically. Corm – It is a short upright stem, covered with scaly leaves. It is hard as compared to bulbs. Examples: Colocasia, Yam, Saffron Bulb – Stem is reduced and surrounded by scale leaves, modified bulbs can be seen. Examples: Tulips, Lilies, Daffodils, Onion, Garlic Tuber – Here the terminal of the stem is fleshy and stores food. The stem contains nodes and internodes but due to swelling, they are not very distinct. Presence of scaly leaves at nodes can be seen as eyes or scars. Examples: Potato, Artichokes 2. Subaerial. These types of stems are present on the ground or partially underground. They are present mostly in plants, which are short-lived and have a weak and herbaceous stem. The stem is used for faster propagation. Runner – It originates from the elongation of the basal internode and runs horizontally over the ground. It carries bud and anchors the soil with the help of root development at nodes. It gives rise to a new plant. Examples: Grasses, Cynodon, Oxalis Stolon – A short and weak aerial branch arises from the main axis it bends down and touches the ground forming roots. Examples: Mint, Strawberry Sucker – Sucker arises from the underground portion of the stem, it grows horizontally under the soil and then comes above the ground. It develops adventitious roots and shoots with leaves and forms a new plant. Examples: Chrysanthemum, banana, pineapple. Offsets – They are found mostly in aquatic plants. A lateral branch arises having short internodes. At nodes, rosettes of leaves develop at the upper portion and roots below. Examples: Pistia, Eichornia Aerial Stem Modification ▪ In some plants, the aerial part of the stem and buds get modified to perform various functions such as support, climbing, photosynthesis and vegetative propagation. Tendrils – These are coiled and a delicate part, which are used for climbing. They develop from the axillary bud. Examples: grapevines, watermelons, pumpkin, cucumber Bulbils – It is a modified axillary bud, it stores food and becomes fleshy. It detaches from the mother plant and develops into a new plant. Examples: Dioscorea Cladode and Phylloclade – These are modified stems, which are green and perform photosynthesis. They become fleshy. Leaves are reduced to spines. These are commonly found in xerophytic plants to reduce water loss. Examples: Opuntia, Euphorbia, Asparagus Thorns – These are developed from axillary buds. They are pointed, woody and hard, spiny structures, which provide protection from grazing animals. Examples: Bougainvillea, lemon ▪ Leaves are the main sites for photosynthesis: the process by which plants synthesize food. ▪ Most leaves are usually green, due to the presence of chlorophyll in the leaf cells. However, some leaves may have different colors, caused by other plant pigments that mask the green chlorophyll. ▪ The thickness, shape, and size of leaves are adapted to the environment. Each variation helps a plant species maximize its chances of survival in a particular habitat. ▪ Usually, the leaves of plants growing in tropical rainforests have larger surface areas than those of plants growing in deserts or very cold conditions, which are likely to have a smaller surface area to minimize water loss. ▪ Each leaf typically has a leaf blade called the lamina, which is also the widest part of the leaf. ▪ Some leaves are attached to the plant stem by a petiole. Leaves that do not have a petiole and are directly attached to the plant stem are called sessile leaves. ▪ Small green appendages usually found at the base of the petiole are known as stipules. Most leaves have a midrib, which travels the length of the leaf and branches to each side to produce veins of vascular tissue. ▪ The edge of the leaf is called the margin. Leaves that do not have a petiole and are Stipules, small leaf-like growths near the directly attached to the plant stem are called base of the petiole, mayor may not be sessile leaves. present. ▪ Within each leaf, the vascular tissue forms veins. The arrangement of veins in a leaf is called the venation pattern. Monocots and dicots differ in their patterns of venation. ▪ Monocots have parallel venation; the veins run in straight lines across the length of the leaf without converging at a point. ▪ In dicots, however, the veins of the leaf have a net-like appearance, forming a pattern known as reticulate venation. One extant plant, the Ginkgo biloba, has dichotomous venation where the veins fork. MONOCOT DICOT ▪ The arrangement of leaves on a stem is known as phyllotaxy. The number and placement of a plant’s leaves will vary depending on the species, with each species exhibiting a characteristic leaf arrangement. Leaves are classified as either alternate, spiral, or opposite. ▪ Plants that have only one leaf per node have leaves that are said to be either alternate—meaning the leaves alternate on each side of the stem in a flat plane. Spiral, meaning the leaves are arrayed in a spiral along the stem. In an opposite leaf arrangement, two leaves arise at the same point, with the leaves connecting opposite each other along the branch. ▪ If there are three or more leaves connected at a node, the leaf arrangement is classified as whorled. ▪ Leaves may be simple or compound. ▪ In a simple leaf, the blade is either completely undivided—as in the banana leaf— or it has lobes, but the separation does not reach the midrib, as in the maple leaf. ▪ In a compound leaf, the leaf blade is completely divided, forming leaflets, as in the locust tree. Each leaflet may have its own stalk, but is attached to the rachis. ▪ A palmately compound leaf resembles the palm of a hand, with leaflets radiating outwards from one point. Examples include the leaves of poison ivy, the buckeye tree, or the familiar houseplant Schefflera sp. (common name “umbrella plant”). ▪ Pinnately compound leaves take their name from their feather-like appearance; the leaflets are arranged along the midrib, as in rose leaves (Rosa sp.), or the leaves of hickory, pecan, ash, or walnut trees. Simple Leaf Palmately Pinnately Compound Leaf Compound Leaf Simple Leaf Palmately Pinnately Compound Leaf Compound Leaf LEAF SHAPE ▪ Plant tissue systems fall into one of two general types: meristematic tissue, and permanent (or non-meristematic) tissue. ▪ Meristematic tissue is analagous to stem cells in animals: meristematic cells are undifferentiated continue to divide and contribute to the growth of the plant. In contrast, Permanent Tissue consists of plant cells that are no longer actively dividing. ▪ Meristems produce cells that quickly differentiate, or specialize, and become permanent tissue. ▪ Such cells take on specific roles and lose their ability to divide further. They differentiate into three main tissue types: dermal, vascular, and ground tissue. Each plant organ (roots, stems, leaves) contains all three tissue types: ▪ Dermal tissue covers and protects the plant, and controls gas exchange and water absorption (in roots). Dermal tissue of the stems and leaves is covered by a waxy cuticle that prevents evaporative water loss. ▪ Stomata are specialized pores that allow gas exchange through holes in the cuticle. Unlike the stem and leaves, the root epidermis is not covered by a waxy cuticle which would prevent absorption of water. ▪ Root hairs, which are extensions of root epidermal cells, increase the surface area of the root, greatly contributing to the absorption of water and minerals. ▪ Trichomes, or small hairlike or spikey outgrowths of epidermal tissue, may be present on the stem and leaves, and aid in defense against herbivores. ▪ Ground tissue carries out different functions based on the cell type and location in the plant, and includes parenchyma (photosynthesis in the leaves, and storage in the roots), collenchyma (shoot support in areas of active growth), and schlerenchyma (shoot support in areas where growth has ceased)is the site of photosynthesis, provides a supporting matrix for the vascular tissue, provides structural support for the stem, and helps to store water and sugars. ▪ Vascular tissue transports water, minerals, and sugars to different parts of the plant. Vascular tissue is made of two specialized conducting tissues: xylem and phloem. ▪ Xylem tissue transports water and nutrients from the roots to different parts of the plant, and also plays a role in structural support in the stem. ▪ Phloem tissue transports organic compounds from the site of photosynthesis to other parts of the plant. The xylem and phloem always lie adjacent to each other in a vascular bundle. ▪ In dicot roots, the xylem and phloem of the stele are arranged alternately in an X shape, whereas in monocot roots, the vascular tissue is arranged in a ring around the pith. ▪ In addition, monocots tend to have fibrous roots while eudicots tend to have a tap root (both illustrated above). ▪ In dicot stems, vascular bundles are arranged in a ring toward the stem periphery. ▪ In monocot stems, the vascular bundles are randomly scattered throughout the ground tissue. ▪ Monocots leaves tend to have parallel veins of vascular tissue in leaves, while dicots tend to have branched or net-like veins of vascular tissue in the leaves. ▪ In sexual reproduction, plants exhibit the complex cycle called alternation of generations. ▪ In this cycle, a plant undergoes two phases, or generations: a haploid generation called gametophyte; and a diploid called sporophyte.  Flowering plants make use of flowers for sexual reproduction. Sexual reproduction in plants takes place in flowers. The complete flower typically consists of four parts: 1. Petals 2. Sepals 3. Stamen (male reproductive part) 4. Pistil/Carpel (female reproductive part) Complete flower Imperfect flower bears only one sexual reproductive organ – either male or female.  Stamen (male reproductive part) consists of anther and filament. ▪ Anther - sac-like structure that produces and stores pollen. ▪ Filament supports the anther.  The pistil (female reproductive part) comprises three parts- stigma, style, and ovary. ▪ Stigma - topmost part of a flower. ▪ Style - long tube which connects the stigma to the ovary. ▪ Ovary - contains a lot of ovules. It is the part of the plant where the seed formation takes place. Complete flower  A flower may consist of either stamen or pistil or both. Based on this, a flower can be either unisexual or bisexual. A bisexual flower is composed of all the four parts. A plants like papaya and cucumber produce only unisexual flowers. Cucumber flower  In order to form a zygote, male gametes in pollen grains have to fuse with egg in the ovule. This is achieved by the process called POLLINATION. POLLINATION is the process of transferring pollen grains from the anther – male part of a flower, to the stigma – female part of a flower. ▪ Two types: ▪ Self-pollination ▪ Cross-pollination  A pollination where the pollen transfer takes place between the anther and stigma of the same flower. Pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant.  A pollination where the pollen transfer takes place between the anther and the stigma of different flowers of the same plant or different plants of the same species. the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species.  Pollination takes place with the help of certain agents so-called pollinators. Insects, water, birds, wind, etc. Once pollen gets transferred to the stigma the male gametes from pollen grains release and fuses with egg in the ovule to form a zygote. This process of fusion of gametes is called fertilization. The zygote thus formed, divides and develops into an embryo, and later into a seed. The ovary develops into a fruit. Angiosperm Life Cycle ▪ In asexual reproduction, part of the parent plant is used to generate a new plant. 1. GRAFTING - artificial method of asexual reproduction used to produce plants combining favorable stem characteristics with favorable root characteristics 2. CUTTING - A cutting is a section of plant such as a modified stem, leaf, or root used for vegetative propagation that forms either adventitious shoots, adventitious roots (stem and single node cuttings), or both (root and leaf cuttings). 3. LAYERING - Layering is a method in which a stem attached to the plant is bent and covered with soil. 4. MICROPROPAGATION - (also called plant tissue culture) is a method of propagating a large number of plants from a single plant in a short time under laboratory conditions. This method allows propagation of rare, endangered species that may be difficult to grow under natural conditions, are economically important, or are in demand as disease-free plants ▪ https://www.getsmidge.com/pages/how-digestion-works ▪ https://courses.lumenlearning.com/suny-ap2/chapter/chemical-digestion-and-absorption-a- closer-look/ ▪ https://quizizz.com/admin/quiz/6046560d320b29001b8c8feb/functions-of-the-circulatory-system ▪ https://www.niddk.nih.gov/news/media-library/11236 ▪ https://socratic.org/questions/what-are-the-somatic-nervous-system-parasympathetic-nervous- system-sympathetic-n ▪ https://www.slideshare.net/itutor/plant-organs ▪ https://organismalbio.biosci.gatech.edu/growth-and-reproduction/plant-development-i-tissue- differentiation-and- function/#:~:text=The%20shoot%20system%20consists%20stems,and%20minerals%2C%20is% 20usually%20underground. ▪ https://byjus.com/neet/different-stem-modifications-with-examples/ ▪ https://bpb-us- w2.wpmucdn.com/sites.gatech.edu/dist/6/1810/files/2017/07/Monocot_vs_Dicot.png