6.4: Organisation and Specialisation of Cells Flashcards
What are cells?
The basic unit of life.
State the order of size of organic components, starting from smallest.
Organelle, specialised cells, tissues, organsm organ system, organism
What does it mean for a cell to be differentiated?
They are specialised to carry out specific functions
What are erythrocytes?
Red blood cells
How are erythrocytes specialised?
-Flattened bioconcave shape
-Flexible
-Do not contain a nucleus or many other organelles
Why do erythrocytes have a bioconcave shape?
To increase their surface area : volume ratio, to increase the rate of diffusion, which allows them to squeeze through blood vessels
Why are erythrocytes flexible?
To squeeze through narrow capillaries and blood vessels
Why do erythrocytes not contain a nucleus?
To make space for haemoglobin, which binds to oxygen for it to be stored and transported oxygen around the body.
What are neutrophils?
A type of white blood cell that plays an essential role in the immune system
How are neutrophils specialised?
-Have a multi-lobed nucleus
-Cytoplasm contains many enzymes used to attack pathogens
-Performs phagocytosis
Why do neutrophils have a multi-lobed nucleus?
Because it makes it easier for them to squeeze through small gaps, to get to the site of infections.
What are sperm cells?
Male gametes.
What is the function of sperm cells?
To deliver genetic information to the female gamete
How are sperm cells specialised?
-Have tail/flagellum
-Aerosome on head contains digestive enzymes, released to digest the protective layers around the ovum
-Have many mitochondria that contain ATP
Why do sperm cells have a tail?
So they are capable of movement
Why do sperm cells contain many mitochondria?
To hold ATP, which supplies the energy needed to swim
Why do sperm cells have digestive enzymes in the aerosome on their heads?
To digest the protective layers around the ovum, which allows the sperm to penetrate, leading to fertilisation.
Where are palisade cells found?
In the mesophyll of a plant
How are palisade cells specialised?
-Contain chloroplasts
-Cells are rectangular box shapes
-Have thin cell walls
-Contain large vacuoles
-Chloroplasts can move within the cytoplasm
Why do palisade cells contain chloroplasts?
To absorb large amounts of light for photosynthesis
Why are palisade cells rectangular box shapes?
So they can be closely packed to form a continuous layer
Why do palisade cells have thin cell walls?
To increase the rate of diffusion of CO2
Why do palisade cells contain large vacuoles?
To maintain turgor pressure
Why can chloroplasts move within the cytoplasm in palisade cells?
To absorb more light
Where are root hair cells present?
At the surfaces of roots, near growing tips in a plant
How are root hair cells specialised?
-Have long extensions called root hair.
Why do root hair cells have root hair?
To increase the surface area of the cell, which maximises uptake of water and minerals from the soil.
What do pairs of guard cells form?
Small openings called stomata, found on the surfaces of leaves on a plant.
What are stomata necessary for?
Carbon dioxide to enter plants for photosynthesis
What happens to guard cells when they lose water?
They become less swollen as a result of osmotic forces, and change shape. The stoma closes to prevent further water loss.
Which side of the cell walls of a guard cell is thicker?
The side of the stoma
Why is one side of the cell wall of a guard cell thicker?
So the cell does not change shape symmetrically as its volume changes
What are the 4 main categories of tissue in animals?
Nervous tissue, epethelial tissue, muscle tissue and connective tissue
What is a tissue?
A collection of differentiated cells that have a specialised function. Each tissue is adapted for a particular function within the organism.
What is a nervous tissue adapted for?
Supporting the transmission of electrical impulses
What is an epithelial tissue adapted for?
Covering body surfaces, internal and external
What is muscle tissue adapted for?
Contracting
What is connective tissue adapted for?
Either holding other tissues together or as a transport medium
What is squamous epithelium tissue?
Animal tissue made up of specialised squamous epithelial cells, also known as “pavement epithelium”
What are the features of squamous epithelium tissue?
-Thin (only one cell thick)
-Present when rapid diffusion across a surface is essential
-Forms the lining of the lungs
Why is squamous epithelium tissue one cell thick?
Because of the flat cells that make it up, and to allow rapid diffusion
Why does squamous epithelium tissue form the lining of the lungs?
To allow rapid diffusion of oxygen into the blood
What is ciliated epithelium tissue?
Animal tissue made up of ciliated epithelial cells
What are the features of ciliated epithelium tissue?
-Cells have cillia on one surface
-Line the trachea
-Goblet cells are also present within the tissue
Why does ciliated epithelium tissue line the trachea?
Because the cilia on its surface causes mucus to be swept away from the lungs
Why does ciliated epithelium tissue contain goblet cells?
To release mucus to trap any unwanted particles, which prevents them from reaching the alveoli when in the lungs.
What is cartilage?
Connective tissue found in the outer ear, nose and at the ends of and between bones
What does cartilage contain?
Fibres of elastin and collagen. Composed of chondrocyte cells embedded in an extracellular matrix
What are the properties of cartilage?
Firm and flexible
What is the function of cartilage in bones?
Prevents the ends of bones from rubbing together and causing damage
What is muscle?
Tissue that has to contract to move bones and therefore other parts of the body.
What do skeletal muscle fibres contain?
Myofibrils, which contain contractile proteins
What are the two types of plant tissue?
Epidermis tissue and vascular tissue
What are epidermis tissues?
Plant tissues that are adapted to cover plant surfaces
What are vascular tissues?
Plant tissues that are adapted for transport of water and nutrients
What is the epidermis?
-A single layer of closely packed cells, covering the surfaces of plants. Usually covered by a waxy, waterproof cuticle to reduce water loss
What feature of plants is present in the epidermis, and what is its function?
Stomata, allow carbon dioxide, water vapour and oxygen in and out
What is xylem tissue?
Vascular tissue responsible for transport of water and minerals throughout plants.
What is xylem tissue composed of?
Vessel elements - Elongated, dead cells. Walls of these cells are strengthened by lignin
What is xylem strengthened by?
Walls of the dead xylem cells are strengthened by lignin.
What is phloem tissue?
A type of vascular tissue, responsible for transport of organic nutrients from leaves and stems to all parts of the plant where it is needed.
What is phloem tissue composed of?
Columns of sieve tube cells, seporated by perforated walls called sieve plates.
What is an organ?
A collection of tissues that are adapted to perform a particular function in an organism
What is an organ system?
A collection of organs working together to carry out a major function in the body.
