Cell Diversity

Previous Exam Questions

Higher LevelOrdinary Level2006 Q62007 Q11, Q142004 Q82006 Q142003 Q42003 (Sample)

TissueTissue A tissue is a group of similar cells that carry out the same function.

Plant TissuePlant Tissues: (4 main types)Dermal e.g. epidermis (skin)Vascular e.g. xylem, phloemGround e.g. spongy mesophyll in leafMeristematic e.g. cells in root tip that divide by mitosis.

Animal TissueAnimal Tissues: (4 main types) Epithelial e.g. epidermis (skin)Connective e.g. blood, boneNervousMuscular

Plant Tissues - DermalDermal Tissue: e.g. EpidermisDermal tissue surrounds and encloses plants.

Plant Tissues - DermalLocation:Dermal tissue is found in the leaf, stem and roots.

Plant Tissue - DermalAppearance:Epidermal tissue usually contains rectangular cells.The cells have thick, strong walls with a waterproof layer called the cuticle on the outer surface.

Plant Tissue - DermalFunction:To protect the plant.If a cuticle is present, it prevents water loss from the plant.

Plant Tissue - VascularVascular Tissue: e.g. xylem, phloemVascular tissue transports materials around the plant.2 types of vascular tissue- Xylem transports water + dissolved minerals.- Phloem transports food around plant

Plant Tissue - VascularLocation:Xylem and phloem are tubular tissues.They are found in all parts of the plant including the roots, stems & leaves.They are arranged in bundles called vascular bundles

Vascular Tissue

Plant Tissue - VascularXylem - Dead tissue that transports water.

- There are 2 types of xylem tissues: - Tracheids - Vessels

Plant Tissue Vascular (xylem)Appearance - TracheidsTracheids are long narrow tubes formed when the walls of individual cells overlap.Their walls have small openings called pits that allow water to pass from cell to cell.Found in the wood of conifers such as pine trees.

Tracheids

Plant Tissue Vascular (xylem)Appearance VesselsVessels are larger than tracheids.They form a continuous hollow tube.Found in flowering plants, especially in trees where they form the wood.

Plant Tissue Vascular (xylem)Function: Tracheids and vessels both transport water and saltsXylem tissue also strengthens the plant.

Questions????What is a tissue?Name 2 types of animal tissues.Name 2 types of plant tissues and state their functions.Name 2 types of xylem tissues and state their functions.

Plant Tissue Vascular (Phloem)Phloem:Appearance:Have many cells that form long tubes called sieve tubes.The walls at the end of each phloem have many pores sieve plates.Have companion cells containing nuclei.

Plant Tissue Vascular (Phloem)

Plant Tissue Vascular (Phloem)Function:Transports food from the photosynthetic regions to the rest of the plant.Companion cells control the sieve tube element.

Animal TissuesConnective tissue:Joins and supports other parts of the body.Example Adipose tissue, blood, boneNervous tissue:Consists of nerve cells called neurons that carry electrical impulses to and from the brain.

Blood

Questions????Name the 2 types of vascular tissues.How would you describe the appearance of phloem?What is the function of phloem?Give 2 examples of connective tissue.

Tissue CultureTissue Culture:Is the growth of tissues on an artificial medium outside an organism.Growth of cells can be:In-vitro outside the bodyIn-vivo in the body

Tissue CultureIn-vitro growth requires:Correct nutrients e.g vitamins, minerals etcGrowth hormonesSuitable temperatureOxygenSterile environment (no bacteria)

Tissue Culture2 examples of tissue culture:Micro-propagationUse of monoclonal antibodies in cancer research

Tissue CultureMicro-propagation:Is the growth of large numbers of identical plants from pieces of an original plant.The new plants are genetically identical (clones).

Tissue CultureBenefits of micro-propagation:Huge numbers of plants can be formed in a very short time.New plants are genetically identicalProcess is a cheap way to produce new plants

Tissue CultureCancer research:Antibodies grown in an artificial medium are called monoclonal antibodies.Examples include; detecting cancer cells, testing for drugs in blood or urine.

OrgansOrgan:Is a structure composed of 2 or more tissues that work together to carry out one or more functionsExamples:Plant organs roots, stems, leaves,Animal organs brain, heart, lungs

OrgansOrgan system:Consists of one or more organs working together to carry out one or more functions.Examples:Digestive system mouth, stomach, etcCirculatory system heart, blood, lymph vessels etc

Organ Systems

Questions????What is meant by tissue culture?Distinguish between in-vitro and in-vivo.Name 3 conditions that in-vitro growth requires?Give 2 examples of tissue cultures.Describe micro-propagation.Name 2 organs & 2 organ systems

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