Biology Past Paper PDF - Q&A Notes

# 04 - BIOLOGY ## -01- Cells, Tissues, Organs and Systems ### Q&A ### Notes #### Life = - have lifespan - grow in size, reproduce - require energy - produce waste - can repair #### 1) Cells #### LD Cell Theory= - all living organisms are made of cells - cells are the basic organizational unit...

# 04 - BIOLOGY ## -01- Cells, Tissues, Organs and Systems ### Q&A ### Notes #### Life = - have lifespan - grow in size, reproduce - require energy - produce waste - can repair #### 1) Cells #### LD Cell Theory= - all living organisms are made of cells - cells are the basic organizational unit of life - all cells come from pre-existing cells. #### Lo cell types - Eukaryotic cells = larger, multicellular life usually - Prokaryotic cells : less organelles #### 4 functions of organelles = - intake of nutrients - response to stimuli - movement - exchange of gases - Growth, reproduction - waste removal #### Organelles: Structures in a cell that carry out various functions to maintain life ### Summary # 04 - BIOLOGY ## -02- Diffusion and Osmosis ### Q&A ### Notes #### 1) Molecule Movement - Obtain sufficient nutrients and dispose of their Hastes (squaved cubed law) - La done by diffusion, osmosis, active transport - Solution – homogenous, liqurd mixture of two or more sulistances - Solvent - dissolving agent of a solution - Solute - substance dissolved in a solution. #### A) Diffusion-movement of solutes - 4 process by which molecules tend to move from an area of higher concentration to an area of low con. - Concentration- amount of substance in a volume - ↳ Kinetic molecular theory = molecules are always moving, collisions occur between molecules (move Away from one another) - Nutrients - low concentration in cells, high concentration outside of cells - 4 movement of molecules by diffusion is how the Cell fulfills its need - Wastes - high concentration in the cell. low outside - #### B) Osmosis - movement of water - 4 movement of water from high concentration to a low concentration through a Semi-permeable membrane (pores) - e.g. Penicillin weakens bacterial cell walls. water concentration higher outside the cell so when it diffuses in through osmosis, the bacterial cell swells and pups #### C) Water Balance - 4 the environment around the cell determines the direction of water movement, not the cell membrane - 4 without other mechanism, the cell would burst or shrivel - plant vacuoles store Water even when the environment is dirty - cell wall is rigid to prevent bursting or shriveling - animals increase / decrease their amount of water intake - ✗ outtake (urine concentration, water ingestion) - 4 Hypertonic - more Hater Inside cell than outside - 4 Isu-usmotic - Same concentration inside & outside - 4 Hypotonic - more water outside cell than inside - cells are 90% water, 10% Solute ### Summary # 04 - BIOLOGY ## -03- DNA and Genes ### Q&A ### Notes #### A) The Nucleus - contains a set of instructions that determines what each cell will become - #### DNA (Deoxyribonucleic Acid) - tells the cell what proteins to make. proteins fill thousands of functions & determine what the cell does #### 1. Nuclear Envelope - Surrounds DNA, protects it from damage - #### 2. Nuclear Pores - transport of molecules across nuclear envelope Choles in the envelope) #### 3. Nucleolus - transcribe DNA into ribosomal RNA #### RNA (Ribonucleic Acid) - copies instructions from DNA and can be moved more freely around the cell subunits - nucleolus assembles rRNA into ribosomal - 4 RNA is important because ribsomes (make protein) are made of rRNA ### Summary # 04 - BIOLOGY ## -04- Cell Cycle ### Q&A ### Notes - 4 humans are composed of 30 trillion cells - 4 most cells have a limited lifespan and are replaced. - cancer cells have a virtually unlimited lifespan - #### A) The Cell Cycle IPMAT - Describes a cell's lifetime from formation to reproducing to make new cells #### 1) Interphase - cells do activities designed + DNA replicates - #### 2) Cell Division - Cytokinesis - formation of 2 daughter cells via mitosis & - Cell division-process where a parent cell splits into two daughter cells #### Cell Cycle - 1 Interphase - 2 Cell Division - 2.1 Mitosis - Prophase - Metaphase - Anaphase - telophase - 2.2 Cytokinesis - Interphase - 1 Gap 1 - 2 Synthesis - 3 Gap 2 ### Summary # 04 - BIOLOGY ## -05- Cancer ### Q&A ### Notes - at each check point specialized proteins act like stop signs - 4 average lifespan of various human body cells : - Brain (30-50 years), Red Blood (120 days), - Stomach lining (2 days), Liver (200 days), - Intestine lining (3days), Skin (20 days) - 4 cell cycle will not occur if = - 1) not enough nutrients to support cell growth - 2) DNA had not been replicated / is damaged - 3) Chromosomes did not separate #### repair - Cell Death - When a cell has been damaged beyond - 1) Necrosis -cell death due to toxins - 2) Apoptosis - cell death due to the cell killing itself to prevent issues #### 4 In apoptosis, the contents of the cell are packaged and distributed so other cells can use them #### A) What Causes Cancer #### 1) Carcinogens - cancer causing agents that can change DNA (mutations that led to Cancer) - 2) X-rays, UV light, viruses, various chemicals (found in smoke, heavy metals) ### Summary: # 04 - BIOLOGY ## -06- Stem Cells, Differentiation, Tissue Types ### Q&A ### Notes #### Animal Stem Cells - Unspecialized cells within the body that can produce specialized cells - 4 one daughter cell will remain a stem cell, While the other will develop a specialization (eg lung) - 4 primarily found in bone marrow, there for repair (differentiate and replace) damaged cells, have limited differentiation ability (for cells found in the same organ) #### Adult Stem Cells #### Embryonic stem cells. - 4 primary cell in developing embryos, will specialize in the future as the embryo grows (more differentiation potential) #### A) Usage - treatment of leukemia, strokes, hepatitis, spinal cord injuries, Alzheimer's disease, diabetes, heart disease, AIDS etc. - 4 these diseases are all the result of cell death or loss of cellular function, and the ability to replace lost / damaged cells Would allow growth of new healthy cells ### Summary # 04 - BIOLOGY ## -07- Plant Tissue Types ### Notes #### Issues around stem cell research: - 1.) Harvesting stem cells kills and destroys the embryo - 2) Moral, ethical & legal questions arise using human embryos - 3) A human being can be cloned - #### Plant Stem cells - Meristems = unspecialized cells in plants found in the growing tips of roots & stems and in a layer in the stem called the cambium (thickens the stem) - 4 active throughout the life of a plant #### Specialized Cells #### Regeneration-process whereby a body part is replaced/regrown - 4 some animals have the unique ability to vegrow limbs, tails, eye lenses, parts of the heart etc. - e.g. Salamander - mitosis is responsible for regenerating the cells that will eventually specialize and create a new limb - e.g. The human liver is the only organ that naturally regenerates - Human fingertips have limited ability to regenerate = in young children, an amputated fingertip that is cleaned and covered with a simple dressing can regenerate #### A) PROCESS OF CELL SPECIALIZATION - Cell Specialization - process in which cells develop in different ways to perform particular functions - Differentiation - eig animal cells → lung cells. skin cells. brain cells. - plant cells → xylem, phoem in the root /stem / leaf - 4 stem cells specialize as an organism matures. most adult Stem cells are involved in the replacement of damaged tissue - e.g. found in skin, blood, neural tissue - 4 adult stem cells from the tissue of one organ can regenerate tissue in another organ - e.g. adult blood stem cells regenerating liver, Kidney and brain cells - Organisms have a hierarchical organization: - increasing levels - Structures can be organised into - Organelles - specialize to perform tasks in cells - cells - performs a task - tissues- collection of cells performing the same task - organs - collection of tissues performing complex task - systems - collection of organs performing a complex task - 4 cells group together & become specialized to perform tasks - TISSUES = group of cells similar in Structure & perform common or related functions. #### B) TISSUE TYPES - 1) Epithelial Tissue (lining surfaces, barrier formation) - 2) Muscle Tissue (change shape by shortening or lengthening, used for movement) - 3) Nervous Tissue (receive & transfer signals to coordinate body actions) - 4) Connective Tissue (Strengthens. supports, protects, binds or connects cells & tissues) #### (B.1) EPITHELIAL & CONNECTIVE TISSUE - 4 epithelial tissue is made up of tightly packed cells that form a protective barrier. may be 1≤ cell(s) thick - 4 connective tissue jorns other tissues together - eig. Skin Epithelium/cells - arts as a semi permeable bamer between the inside & outside of the body - Columnar Epithelial Cells - columns of cells that line the small intestine. Stomach & glands (cilia absorhs nutrient) - types of connective tissues = tendons & ligaments, bones: cartilage, adipose tissue, blood - e.g. Tendons = connect muscles to bunes - Ligaments = connect bunes to bones/ - Adipose : fat storing cells (for energy, provide cushioning. #### (B.2) MUSCLE TISSUE - 4 types of muscle tissues = - → more under conscious control - 1) Skeletal Muscle = when moring legs/arms - 2) smooth Muscle: present in blood vessels, stomach etc. - 3) Cardiac Muscle: found only in the heart - muve automatically - (tissues look striped) - → cells that line up in the same direction, attached to bone so it moves #### (B.3) NERVOUS TISSUE - 4 made of nerve cells which are capable of creating messages called impulses, and transmitting them through the body - 4 nerve cells transport signals via an electrical change (moving ions like Na+, K+, Cl-) across their membrane) & through chemical messengers from one cell to another - 4 nerve cells receive info from Inside & outside the body, and transport info to & from the brain #### Neuron - Axons = long projections used to carry messages. - courdinate body actions, relay signals to / from the brain/ Spinal cord muscles / glands, detect info from their environment & trigger a body response - Supported by glial cells (not connective tissue) #### C) PLANT TISSUES #### ((.1) Epidermal Tissue - → epidermal tissue on both the top & underside of the leaf is clear & thin - Stromate - specialized guard cell that form a tiny opening or pore that allows CU₂, H₂O vapour & o₂ to move into/out of the leaf - 4 most stromata are found on the underside of the leaf #### (C.2) Ground Tissue - 4 most of the plant is made up of ground tissue. the function | Tissue Type | Graph | Major Functions | |---|---|---| | Epithelial | | Connective | | Muscle | | Nervous | - depends on where it is found on the plant - eig. in the roots, ground tissue is involved in food & Water storage in the leaves, photosynthesis & gas exchange occurs in specialized ground tissive called mesophyll #### (C.3) Vascular Tissue - 4 transports Water & nutrients throughout the plant. two types: - 1) Xylem = responsible for the movement of water & minerals from the routs up to the leaves (used in photosynthesis) - 2) Phloem: transports the sugar produed during photosynthesis to other parts of the plant to provible energy for all cellular processes - 4 Xylem tends to be closer to the center of the root/ stem. while phloem is closer to the outside - 4 Xylem is often larger & needs more water - ☆ Xylem aren't alive. cells form the shape. link & die #### (C.4) Root Tissue - 4 dead cells for root cap on end. meristern is more coloured. - 4 xylem are large cells. phloem are nearby. cambium is near. - other tissues are ground tissues. epidermal tissues aren't visible | Tissue Type | Graph | Major Functions | |---|---|---| | Meristematic | | Epidermal | | Ground | | Vascular | Scanned with CS CamScanner™