BioAdditonal: Cells, tissues and organs

Animals and Plant cells both have:

Nucleus Contains genetic material, which controls the activities of the cell Cytoplasm Most chemical processes take place here, controlled by enzymes Cell membrane Controls the movement of substances into and out of the cell Mitochondria Most energy is released by respiration here Ribosomes Protein synthesis happens here

Plant cells also have: 

Cell wall Strengthens the cell Chloroplasts Contain chlorophyll, which absorbs light energy for photosynthesis Permanent vacuole Filled with cell sap to help keep the cell turgid

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Animal and Plant cells

Function of cells which animal and plant cells have in common:

  • Nucleus - Contains genetic material, which controls the activities of the cell
  • Cytoplasm - Most chemical processes take place here, controlled by enzymes
  • Cell membrane - Controls the movement of substances into and out of the cell
  • Mitochondria - Most energy is released by respiration here
  • Ribosomes - Protein synthesis happens here

Plant cells also have extra parts:  Extra parts of plant cells

  • Cell wall - Strengthens the cell
  • Chloroplasts - Contain chlorophyll, which absorbs light energy for photosynthesis
  • Permanent vacuole - Filled with cell sap to help keep the cell turgid
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Bacteria and Yeast

Bacteria - A bacterium is a single-celled organismA bacterial cell has a different structure to an animal or plant cell. It's features:

  • Cytoplasm
  • Membrane
  • Surrounding Cell Wall
  • BUT the genetic material is not in the nucleus (as it doesn't have one!)

Yeast - Yeast is a single-celled organism.Like bacterial cells, yeast cells have cytoplasm and a membrane surrounded by a cell wall. But unlike bacterial cells, yeast cells have a nucleus. It's features

  •  Cytoplasm
  • Membrane
  • Surrounding Cell Wall 
  • BUT the genetic material is in the nucleus <--(difference from bacteria)-->


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Cells and transport

Specialised Cells - Cells may be specialised for a particular function. Their structure will allow them to carry this function out. 

Leaf Cell - Absorbs light energy for photosynthesis - Packed with chloroplasts. Regular shaped, closely packed cells form a continuous layer for efficient absorption of sunlight.

Root Hair Cell - Absorbs water and mineral ions from the soil - Long 'finger-like' process with very thin wall, which gives a large surface area.

Sperm Cell - Fertilises an egg cell - female gamete - The head contains genetic information and an enzyme to help penetrate the egg cell membrane. The middle section is packed with mitochondria for energy. The tail moves the sperm to the egg. 

Red Blood Cells - Contains haemoglobin to carry oxygen to the cells. - Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of haemoglobin.

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Diffusion 1

Dissolved substances have to pass through the cell membrane to get into our out of a cell - diffusion is one of the processes that allows this to happen.

 Diffusion occurs when particles spread.  They move from a region where they are in high concentration to a region where they are in low concentration.

 Diffusion happens when the particles are free to move.  This is true in gases and for particles dissolved in solutions.

Particles diffuse down a concentration gradient, from an area of high concentration to an area of low concentration.  This is how the smell of cooking travels around the house from the kitchen. 

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Diffusion 1 continued

Location                Particles Move                From                        To                     

  • Gut               Digested Food Products     Gut Cavi          Blood in capillary                                                                                                    of villus
  • Lungs            Oxygen           Alveolar air space         Blood circulating                                                                                                around the lungs

Remember, particles continue to move from a high to a low concentration while there is a concentration gradient.  In the lungs, the blood will continue to take in oxygen from the alveolar air spaces provided the concentration of oxygen there is greater than in the blood. Oxygen diffuses across the alveolar walls into the blood, and the circulation takes the oxygen-rich blood away.

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Organs in Animals 1

Multicellular organisms usually contain differentiated cells, adapted for specific functions.  Tissues consist of groups of similar cells. Organs contain different tissues, working together to carry out particular functions. Organ systems contain different organs. The different organ systems work together in an organism.

 Tissues - During the development of a multicellular organism, cells differentiate so that they can carry out different functions. (Differentiation is the process by which a cell becomes a specialised type of cell.)  (A tissue is a group of specialised cells that have a similar structure and function.)

Some tissues + their functions

  • Muscular tissue - Contracts, bringing about movement
  • Glandular tissue - Produces substances such as enzymes and hormones
  • Epithelial tissue - Covers some parts of the body
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Organs in Animals 2

Organs

Organs are made of tissues. A particular organ may contain several different tissues. For example, the stomach is an organ that contains:

  • Muscular tissue - to churn the food and other contents of the stomach
  • Glandular tissue - to produce digestive juices including acid and enzymes
  • Epithelial tissue - to cover the inner and outer surfaces of the stomach

The stomach is one of the organs that form the digestive system. The stomach contains various tissues, and each tissue is made of a particular type of cell. In order of increasing size and complexity:

cells → tissues → organ (the stomach) → organ system (the digestive system)

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Organs in Animals 3

The digestive system 

Organ systems are groups of organs that carry out a particular function. The human body has several organ systems, including:

  • The nervous system
  • The respiratory system
  • The reproductive system
  • The digestive system

its main tissues and organs, and their functions:

Pancreas and salivary glands-  Produce digestive juices Stomach-  Digests food Liver-  Produces bile Small intestine-  Digest and absorb soluble food Large intestine-  Absorbs water from undigested food, producing faeces

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Organs in Plants 1

Tissues

The table shows some examples of plant tissues and their functions.

  • Epidermal tissue - Covers the plant
  • Mesophyll - Carries out photosynthesis
  • Xylem and phloem - Transport of substances around the plant
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Organs in Plants 2

Organs

Examples of plant organs include:

  • Roots
  • Stems
  • Leaves

Leaves

Leaves are adapted to absorbing sunlight for photosynthesis

Adaptations and Purpose:

Chlorophyll -  To absorb sunlight Large surface area -  To absorb more light Stomata -  To let carbon dioxiddiffuse into the leaf Thin -  Short distance for carbon dioxide to diffuse into leaf cells Network of veins -  To support the leaf and transport water and carbohydrates

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Organs in Plants 3 continued

Adaptions and Purposes

Thin, waxy cuticlemade of wax -  To protect the leaf without blocking out light

Thin, transparentepidermis -  To allow more light to reach the palisade cells

Layer of palisade cells on the top surface -  To absorb light

Many chloroplasts in the palisade cells -  To increase absorption of light

Spongy mesophyllinside the leaf -  Air spaces allow carbon dioxide to diffuse through the leaf, and increase the surface area

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