Organisation and Specialisation of Cells Flashcards
What are the levels of organisation in multicellular organisms?
- Specialised cells
- Tissues
- Organs
- Organ systems
- Whole organism
What are some examples of specialised animal cells?
- Erythrocytes
- Neutrophils
- Sperm cells
How are erythrocytes adapted for their function?
- Have a flattened biconcave shape which increases their surface area to volume ratio
- No nucleus to maximise space for haemoglobin
- Flexible so they are able to squeeze through capillaries
How are neutrophils adapted for their function and what is their role?
- Multi-lobed nucleus which allows them to squeeze through small gaps to a site of infection
- Granular cytoplasm contains many lysosomes that contain enzymes used to attack pathogens
- Role:
How are sperm cells adapted for their function?
- Tail or flagellum to allow them to move
- Many mitochondria to supply energy needed to move the flagella
- Head of sperm contains enzymes which are released to digest the protective layers around the ovum, allowing the sperm to penetrate, leading to fertilisation
What are some examples of specialised plant cells?
- Palisade cells
- Root hair cells
- Guard cells
How are palisade cells adapted for their function?
- Rectangular shape so they can be closely packed in to form a continuous layer
- Thin cell walls, increasing rate of diffusion of carbon dioxide
- Large vacuole to maintain turgor pressure
- Chloroplasts can move within the cytoplasm in order to absorb more light
How are root hair cells adapted for their function?
- Long extensions called root hairs which increase surface area
- This maximises the uptake of water and minerals
How are guard cells adapted for their function?
- Cell wall is thicker on one side so the cell does not change shape symmetrically as the volume changes
- When they lose water and become less swollen, as a result of osmotic forces, they change shape and stoma closes to prevent further water loss
- Necessary for carbon dioxide to enter
What are the four mains categories of tissues in animals?
- Nervous, adapted to support the transmission of electrical impulses
- Epithelial tissue, adapted to cover body surfaces, internal and external
- Muscle tissue, adapted to contract
- Connective tissue adapted to either hold tissues together or as a transport medium
What does squamous epithelial look like?
Very flat
Why is squamous epithelial tissue flat?
Due to the flat cells that make it up and also because it is only one cell thick
Where is squamous epithelial tissue found and why?
- Present when rapid diffusion across a surface is essential
- For example lining of lungs as it allows rapid diffusion of oxygen into the blood (only one cell thick)
What does ciliated epithelium look like?
-Made up of ciliated epithelial cells that have ‘hair-like’ structures called cilia on one surface that waft
Where is ciliated epithelium found and why?
- Lines the trachea
- Causes pathogens that have been trapped by mucus to be wafted away from the lungs
- Prevents infection
What is cartilage?
Connective tissue found in outer ear, nose and at the ends and between of bones
What does cartilage contain?
Fibres of the proteins elastin and collagen
Why is cartilage important?
- Prevents ends of bones from rubbing together and causing damage
- Allows trachea to bend when food is swallowed
- Holds trachea open
What does skeletal muscle contain?
Microfibrils which contain contractile proteins
Why is muscle important?
Shortens in length, to move bones, which allows us to move different parts of the body
What are the specialised plant tissues?
- Epidermis
- Xylem tissue
- Phloem tissue
How is epidermis tissues adapted for its function?
Covered by a waxy, waterproof cuticle to reduce the loss of water by evaporation
Contains guard cells to allow carbon dioxide to diffuse in and out
Single layer so thin for diffusion
What is epidermis made up of?
Single layers of closely packed cells covering the surfaces of plants
How is xylem tissue adapted for its function?
Strengthened with waterproof material called lignin which provides structural support and prevents water loss
Elongated dead cell vessels to allow constant flow
What kind of tissue is xylem tissue?
Vascular tissue
What is xylem tissue responsible for?
Transport of water and minerals throughout plants
What is phloem tissue responsible for?
Transport of organic nutrients, particular sucrose, from leaves and stems where it is made by photosynthesis to all parts of plant where it is needed
What is phloem tissue composed of?
Sieve tube elements separated by perforated walls called sieve elements
What is an organ?
Collection of tissue that are adapted to perform a particular function
What are the organ systems?
- Digestive system
- Cardiovascular system
- Gas exchange system
