Romania Clasa a X-a Biology

1. Plant and animal tissues

Plant tissues · Animal tissues

• Anatomy of Flowering Plants – Anatomy is the study of the inside structure of a plant, seen by cutting thin slices (sections). Plant cells form tissues, and tissues form three tissue systems: epidermal (the skin), ground (the filling) and vascular (xylem and phloem pipes). Dicots and monocots differ in how these systems are arranged in their root, stem and leaf.
• Structural Organisation in Animals: the Frog – In animals, cells form tissues, tissues form organs and organs work together in organ systems. The common Indian frog (Rana tigrina, now Hoplobatrachus tigerinus) is a good model: its body has a head and trunk, and inside it has digestive, respiratory, circulatory, nervous, excretory, endocrine and reproductive systems. It breathes through both skin and lungs, has a 3-chambered heart and lays eggs in water.

2. Nutrition

Autotrophic nutrition · Heterotrophic nutrition · Digestive system of mammals · Respiration · Circulation · Excretion

• Life Processes and Photosynthesis – Life processes are the jobs every living body must keep doing to stay alive: nutrition, respiration, transport and excretion. Green plants do nutrition by photosynthesis: using sunlight and chlorophyll, they turn carbon dioxide and water into glucose and give out oxygen.
• Human Digestive System and Heterotrophic Nutrition – Heterotrophs take ready-made food from other living things. Humans are holozoic: we eat whole food and break it down in a long tube, the alimentary canal. Teeth, saliva, stomach acid, enzymes, bile and pancreatic juice cut big food molecules into small ones that villi in the small intestine absorb into blood.
• Respiration in Plants – Respiration breaks food like glucose to release energy stored as ATP. Plants take in O₂ through stomata and lenticels. Glycolysis in the cytoplasm splits glucose into two pyruvates. Without O₂, pyruvate is fermented to ethanol or lactic acid. With O₂, pyruvate enters the mitochondrion, runs the Krebs cycle, and the electron transport system uses O₂ to make most of the ATP: up to 38 per glucose. The same path also builds molecules (amphibolic). RQ = CO₂ given out ÷ O₂ taken in.
• Body Fluids and Circulation – Blood and lymph are the body's transport fluids. Blood is plasma (about 55%) plus formed elements: RBCs, WBCs and platelets. Blood groups (ABO, Rh) depend on antigens on RBCs. A clot forms when fibrinogen turns into fibrin threads. The human heart has four chambers and pumps blood through two loops: to the lungs and to the body (double circulation). The SA node starts each beat; one beat is a cardiac cycle of about 0.8 s, recorded as an ECG with P, QRS and T waves. Cardiac output = stroke volume × heart rate ≈ 5 L/min.
• Excretory Products and their Elimination – Animals must remove nitrogen waste. Ammonia is most toxic and needs lots of water; urea is less toxic; uric acid needs least water. Humans are ureotelic. Each kidney has about a million nephrons. Urine forms in three steps: glomerular filtration (about 125 mL/min, 180 L/day), reabsorption (about 99% taken back) and secretion. The loop of Henle and vasa recta make the medulla salty by a counter-current mechanism, so urine can be concentrated. ADH, the renin-angiotensin-aldosterone system and ANF control water and salt. Lungs, liver, skin and sweat also help. Failed kidneys need dialysis or a transplant.

3. Relation functions

Sensitivity and movement · Locomotion

• Neural Control and Coordination – Coordination means organs working together. The nervous system does this fast, using neurons. A neuron has a cell body, dendrites and an axon; many axons have a myelin sheath with nodes of Ranvier. The central nervous system (brain and spinal cord) processes information; the peripheral nervous system (nerves) carries it. The PNS has a somatic part (skeletal muscles) and an autonomic part (sympathetic and parasympathetic) for internal organs, the visceral system. At rest the axon is polarised: inside −, outside +, about −70 mV. A stimulus lets Na+ rush in, creating an action potential that travels along the axon. At a synapse, neurotransmitters carry the signal to the next neuron.
• Locomotion and Movement – Movement is a change in position of a body part; locomotion is moving the whole body from place to place. Cells move in three ways: amoeboid, ciliary and flagellar. Humans use muscular movement. Muscles are skeletal, visceral or cardiac. A skeletal muscle is made of fibres, each packed with myofibrils made of repeating sarcomeres of actin and myosin. A nerve signal releases Ca2+, myosin heads pull actin using ATP, and the sarcomere shortens (sliding filament theory). The skeleton has 206 bones. Joints can be fibrous, cartilaginous or synovial (ball and socket, hinge, pivot, gliding, saddle). Disorders include myasthenia gravis, tetany, muscular dystrophy, arthritis, osteoporosis and gout.

4. Reproduction

Reproduction in plants · Reproduction in animals

• Sexual Reproduction in Flowering Plants – Sexual reproduction joins a male and a female gamete, mixing DNA from two parents and creating more variation. In a flower, pollen from the anther reaches the stigma (pollination), grows a pollen tube to the ovule, and the male gamete fuses with the egg (fertilisation). The zygote becomes the embryo, the ovule becomes the seed and the ovary becomes the fruit.
• Reproduction in Human Beings and Reproductive Health – At puberty, hormones from the brain make the testes and ovaries start working. The male system makes and carries sperm; the female system makes eggs and provides a place (uterus) where a baby develops. Fertilisation happens in the oviduct, and the embryo is fed through the placenta. Reproductive health includes safe choices, contraception, avoiding female foeticide, and preventing sexually transmitted diseases such as HIV/AIDS.

5. Ecological imbalances

Ecological imbalances

Coming soon