Cells And Tissues (ps4) Flashcards
Draw a typical plant cell
So drawing with labels
State the function of Cell wall
The cell encloses the cell and gives it shape and support. It is composed of cellulose fibres, held together with pectin, which are laid down in a cross cross fashion in order to give the wall strength (THINK SHREDDIES). The cell is FULLY PERMEABLE allowing substances to pass through it.
State the function cell membrane
The cell membrane is living. The cell membrane is comparable to a sac that holds the cell contents. It is SELECTIVELY PERMEABLE allowing some materials to pass through but not others
State function of nucleus
The nucleus, which is the ‘control centre’ for all cell functions.
It also carries the genetic material of the cell, so plays an essential role in cell division. Contains DNA and RNA.
The nucleus keeps the cell alive- if nucleus dies - cell dies
State the function of vacuole
The vacuole is a membrane bound sack present in most cells, which is full of cell sap. It is up to 98% water, and acts as a store for amino acids and sugars as well as some waste products. Vacuole is the largest organelle in a cell, between 89-95% of the cell. Very large sack, inside is water- cells will only function if the vacuole is full.
Sugars are produced in leaves, left overs are stored in a vacuole, it’s a recycling point for toxins, keeps cell turgid when full of water.
State the function of cytoplasm
The cytoplasm is a jelly-like living material. Contains lots of chemicals which are divided in water and which offer organelles are present. Suspended within the cytoplasm is : Chloroplasts Nucleus Mitochondria
State the function of chloroplasts
Chloroplasts are small bodies , or organelles , which contain chlorophyll, necessary for the process of photosynthesis- they look like a doughnut shape
State function of mitochondria
Mitochondria- are organelles that are the site of cellular respiration, the process that releases energy for cellular processes
They produce their own energy for physiological process. We call this energy ATP
The place where sugars are broken down and energy released for the physiological processes.
Looks like VIANETTA
Describe where cell division is located within the plant
Cell decision is located in two areas of the plant,
The first is the APICAL MERISTEM - this is a meristem in the apex of the roots or shoots of a plant
It cannot be seen with the naked eye
LATERAL MERISTEM
- meristems found between the phloem and xylem tissue in the roots of the stems it dicotyledon plants, usually referred to as CAMBIUM
Describe how plants increase in size - through cell division and enlargement
An increase in size and volume occurs when cells in the meristematic regions of the plant, DIVIDE by mitosis and then ENLARGE.
Following enlargement the cells differentiate into one of the following:
EPIDERMAL TISSUE
PHOTOSYNTHETIC TISSUE
PARENCHYMA TISSUE
MECHANICAL TISSUE
VASCULAR TISSUE
State what is meant by plant tissue
Plant Tissue Definition. Plant tissue is a collection /group of cells of similar shape and size which have the same function.
Each plant tissue is specialized for a unique purpose, and can be combined with other tissues to create organs such as leaves, flowers, stems and roots.
Plant tissues can be divided into
MERISTEMATIC TISSUE EPIDERMAL TISSUE PHOTOSYNTHETIC TISSUE PARENCHYMA TISSUE MECHANICAL TISSUE VASCULAR TISSUE
Describe the characteristics and function of:
PROTECTIVE (EPIDERMAL) TISSUE
Epidermal tissue
This is the protective tissue at the surface of the plant.
This is the ‘skin’ of the plant, - cells are brick like, flattened and closely packed together, often irregular in shape, forming a protective layer of the more delicate tissues beneath.
These cells DO NOT CONTAIN CHLOROPLASTS and the outer cellulose walls are usually thick and impregnated with a waxy material called CUTIN to firm the CUTICLE, is extra protection against pathogens.
The cuticle is impermeable to water and prevents excessive evaporation.
The
Describe the characteristics and function of: MERISTEMATIC TISSUE (CAMBIUM)
Meristematic tissue is structurally the most basic / simplest plant tissue. It occurs at the apical growing points of the plant eg. The top of stem and root and CAMBIUM in stems and roots of dicotyledonous plants. Meristematic cells are small, thin walled, lack vacuoles, (as no need to store) and lack chloroplasts.these are the ONLY cells within the plant that have the ability to divide by a process called Mitosis.
Meristematic cells are very thin walled - so easy to divide.
Describe the characteristics and function of:
VASCULAR - TRANSPORT TISSUE (PHLOEM, XYLEM)
Vascular tissue is transport tissue.
There are two types:
XYLEM - consist of elongated lignified tubes called vessels which conduct water and mineral salts from roots to the leaves.
The movement through the cell is only ever UPRIGHT/UPWARD . They are large vessels that are never ending continuous from roots to leaves. The amount of Xylem vessels are LARGER than the amount of phloem cells.
These cells never stop working or slow down as plants need water and nutrients all year round
XYLEM cells CAN die as they become blocked with lignin- if it dies completely from root to leaf it becomes known as wood
PHLOEM - consist mainly of unlignified cells called sieve tubes, whose function is to covey food materials from the leaves to other parts of the plant
The movement of substances is both DOWNWARDS & UPWARDS - these cells are connected by sieve cells
Phloem cells NEVER die, if a tissue is most active the nucleus can get tired and stop working but they develop companion cells that have only a nucleus - each cell contains one companion cell
Describe the characteristics and function of:
PARENCHYMA (PACKING TISSUE)
Parenchyma tissue is packing tissue and consist of rounded cells packed loosely together -it’s function is to fill the spaces between other tissues and to maintain cell shapes. Parenchyma tissue has large Vacuoles frequently contains starch , minerals and water and, therefore functions as storage tissue.
