Biology: Cell Structure Flashcards
(106 cards)
1
Q
What is a tissue?
A
A tissue is a group of more or less similarly differentiated cells that performs a specific function
2
Q
What groups are plant tissues divided into?
A
Plant tissues are divided into meristematic tissues and permanent tissues
3
Q
Define the term “ Differentiation”
A
Differentiation is the process during which new cells or tissues undergo a change in size, shape and structure in order to perform specific functions
4
Q
Provide a defintion for meristematic tissue
A
Meristematic tissue is actively dividing tissue in which new cells are continually formed by mitosis
5
Q
What are the two types of meristematic tissue?
A
▪︎ Apical meristem
▪︎ Lateral meristem
6
Q
Where is the apical meristem located?
A
The apical meristem is located near the tips of the roots and stems
7
Q
What is the apical meristem responsible for?
A
It is responsible for growth in length by mitosis
8
Q
List the basic structure of the apical meristem
A
☆ The cells are relatively small
☆ The cells are cube shaped
☆ The cell walls are thin
☆ Vacoules are absent
☆ The cell nuclei are larger and prominent
☆ There are no intercellular spaces
9
Q
What is the function of the apical mersitem?
A
New cells that form through mitosis result in the primary growth (growth in length) of the plant
10
Q
Where is the lateral meristem located?
A
The lateral meristem is located between the xylem and phloem in the vascular bundles of dicotyledonous plants and is known as cambium
11
Q
List the basic structure of the lateral meristem
A
◇ It’s cells are similar to those of the apical meristem, except that the cells are flatter and slightly elongated
◇ The cells have thicker cell walls than the cells of the apical meristem
12
Q
What is the function of the lateral meristem?
A
● New cells formed by mitosis result in secondary growth (growth in thickeness) in dicotyledonous stems
13
Q
Account for why sometimes a group of cells in a plant become meristematic?
A
Sometimes a group of cells in a plant become meristematic (divide in inactively) for a particular function, ie; cells that form new cells replace damaged and worn out cells, or cells give rise to lateral roots. These new cells are known as secondary meristematic tissues
14
Q
What does the permanent tissue include?
A
• Epidermis
• Parenchyma
• Sclerenchyma
• Collenchyma
• Vascular Tissues
15
Q
Where is the epidermis located?
A
It forms the outer layers around roots, stems and leaves
16
Q
List the basic structure of the epidermis
A
¤ Epidermal cells are brick shaped and arranged in single layer
¤ The cells are transparent and do not contain chloroplast
¤ There are no intercellular air spaces between the cells
¤ The epidermal cells of leaves and stems are covered by a waxy layer, the cuticle
¤ The brick shaped epidermal cells can be modified, for example into root hairs or the gaurd cells of stoma
17
Q
What are root hairs?
A
Root hairs are unicellular, thin walled outgrowths of the root epidermis
18
Q
What is the function of root hairs
A
They increase the absorption area of the root
19
Q
Where are guard cells mostly located
A
Guard cells are mainly located in the epidermis of the leaf
20
Q
What is a stroma formed by?
A
A stroma is formed by two bean shaped guard cells
21
Q
What are the functions of the epidermis?
A
♡ The epidermis protects the underlying tissues from injury and destination (drying out )
♡ The cuticle prevents excessive moisture loss in leaves, stems and in the plants
♡ The transparent epidermis allows sunlight through for photosynthesis
♡ Root hairs absorb water and mineral salts from the soil
♡ The guard cells of the stroma control the opening and closing of the stomatal pore for gaseous exchange
22
Q
Why is gaseous exchange important in plants?
A
Gaseous exchange in plants is essential for photosynthesis, respiration and for transportation to occur
23
Q
What is the most abundant plant tissue
A
Parenchyma
24
Q
List the basic structure of parenchyma
A
▪︎ Parenchyma cells are large with thin cell walls
▪︎ Large intercellular spaces should occur between cells
▪︎ The cells have vacoules
▪︎ Stem and leaf parenchyma contain chloroplasts
25
What is chorenchyma?
Chlorenchyma is parenchyma containing chloroplast
26
What are the functions of parenchyma?
♧ It's stores food and water
♧ It produces carbohydrates through photosynthesis
♧ The intercellular spaces allows gaseous exchange to take place
♧ The vacoule provides rigidity as a result for tugor pressure exerted by cell sap
27
Where is sclerenchyma found?
Sclerenchyma cells are found in leaves, stems, fruits and roots of plants
28
List the basic structure of sclerenchyma
◇ The cells are evenly thickened by lignin
◇ Each cell has a small lumen (cell cavity)
◇ The cell contents are relatively inactive
◇ There are two types of cells: sclereids and fibres
◇ Sclereids are more or less a round shape
◇ Fibres are more elongated
29
What are the functions of sclerenchyma?
¤ Sclerenchyma serves as a strengthening tissue
¤ It provides mechanical support to the plant
30
Where does collechyma occur?
Collenchyma usually occurs in young herbaceous stems
31
List the basic structure of collenchyma
》 The cells are unevenly thickened with cellulose
》 Most thickening occurs in the corners of the cell walls
32
What are the functions of collenchyma?
□ Collenchyma serves as strengthening tissue
□ It provides mechanical support to the plant
33
What do the vascular tissues consist of?
Vascular tissues consists of xylem and phloem
34
Where are the vascular tissues ( xylem and phloem ) located?
Xylem and phloem are located in the roots, stems and leaves of plants
35
Why is xylem considered a dead tissue?
It is because xylem contains no living materials
36
What does xylem tissue mainly consist of?
Xylem mainly consist of xylem vessels and tracheids
37
List the basic structure of the xylem vessels
• Xylem vessels consist of a series of elongated cells connected end to end
• The individual cells do not contain cytoplasm and are therefore empty and dead
• The transverse walls (cross-walls) are perforated or have disappeared completely to form a continuous tube
• The cellulose cell walls are thickened evenly by lignin; however, the entire wall is not evenly thickened, but lignin forms spiral, ring like or pitted (net) patterns
• This uneven thickening provides additional strength and support to the vessels in that they stretch, remain open, flexible and upright
• The thickened walls are pits that enable lateral transport between the xylem vessels
• In a cross-section, xylem vessels are round. Their round structure provides additional strength and support
38
List the basic structure of tracheids
♡ Tracheids are elongated cells with tapered ends
♡ Water moves more slowly in the tracheids than xylem vessels
♡ Their cell walls are, as in the xylem vessels, thickened by lignin. Pits connect adjacent ends
♡ The tapered ends of the tracheids overlap and also contribute to the strengthening of the tubes and lateral transport
39
What are the functions of xylem?
¤ Water and dissolved mineral salts are transported by the xylem from the roots to the rest of the plant
¤ Xylem serves as strengthening and support tissues for the plants
40
What does ploem consist of, in contrast to xylem
Phloem consists of living cells that, in contrast to xylem, do not contain thickened walls. Phloem tissue mainly consists of sieve tubes and companion cells
41
List the basic structures of the sieve tubes in phloem
□ Sieve tubes consists of elongated living cells that are joined to one another, end to end
□ They are cross walls between the continuous segments are perforated and are called sieve plates
□ The cellulose cell walls of the sieve tubes are thin walled and are not strengthened by lignin
□ Mature sieve tubes have no nucleus and are dependant on the companion cells
42
List the basic structure of the companion cells in the phloem
☆ Companion cells have nuclei
☆ Companion cells are responsible for performing all the metabolic activities of the sieve tubes
43
What are the functions of phloem?
● Transport of produced organic nutrients from the leaves to the rest of the plants
44
List the 4 types of animal tissues
》 Epitheal tissue
》 Connective tissue
》 Muscle tissue
》 Nerve tissue
45
What are the epithelial tissues specialized for?
Epithelial tissue is specialized to form linings that cover internal and external surfaces
46
What are stratified epitheliums? In contrast to simple empithelium
In contrast to simple empithelium, stratified epithelium is when the epithelial tissue consists of more than one layer of cells
47
What are the four types of epithelial tissue?
¤ Squanous epithelium
¤ Cuboidal epithelium
¤ Columnar epithelium
¤ Ciliated epithelium
48
What does the squanous epithelium do?
Squamous epithelium lines the internal walls of the cavities; ie, blood vessels, alveoli, mouth and oesaphagus
49
What is the difference between edothelium and endocardium?
Endothelium are the squanous epithelium that lines blood vessels whereas endocardium are the squanous epithelium that lines the heart
50
List the basic structure of the squanous epithelium
◇ It is a single layer of thin flat cells
◇ The cells are tightly packed and form a Mosaic pattern
◇ The nucleus is horizontally flattened and has an oval shape
51
What are the functions of the squanous epithelium?
¤ It protects the underlying tissues
¤ It is permeable to gases and liquids
¤ It prevents friction
52
What does the cuboidal epithelium do?
The cuboidal epithelium often lines the glands that secrete and absorb substances
53
List the basic structure of the cuboidal epithelium
♡ The cells are more or less cube shaped, ie: the are as long as they are wide
♡ The cell nuclei are round and occur in the center of the ball
54
What are the functions of the cuboidal epithelium?
○ Secretion ( release of useful substances )
○ Absorption ( taking in substances )
55
What does the Columnar Epithelium do?
The Columnar Epithelium lines the alimentary canal, especially the stomach and small intestines. Some Columnar Epithelium cells perform a sensory function in the nose, ears and taste buds on the tongue
56
List the basic structure of the Columnar Epithelium
¤ The cells are elongated and column shaped
¤ The cell nuclei are elongated and occur near the base of the cells
¤ Goblet cells, which secrete mucus, often occur between the Columnar Epithelial cells
57
What are the functions of the Columnar Epithelium?
☆ Absorption
☆ Secretion
☆ Sensation (sensory function)
58
What does the Ciliated Epithelium do?
The Ciliated Epithelium lines the nasal cavities, trachea and brochi in the lungs. It also occurs in the sensory organs; ie: the ears as well as in the fallopian tubes and the uterus
59
What is the basic structure of the Ciliated Epithelium?
* This epithelium consists of Columnar Epithelial cells with exceptionally fine hairs, known as cilia, on the free ends of each cell
* The cilia perform fast, rhythmic, wave like movements in specific direction
* Goblet cells, which secrete mucus, often occur between ciliated epithelial cells
60
What are the functions of the Ciliated Epithelium?
▪︎ Dust particles are trapped in the mucus; movement of the cilia away from the lungs will ensure that the mucus is expelled
▪︎ It helps to detect stimuli in sensory organs
▪︎ Cilia ensure the movement of the ovum in the Fallopian tubes and uterus
61
What does the connective tissue do?
Connective tissue binds, suports or surrounds other tissue or organs
62
What are the 5 types of connective tissue?
》 Areolar connective tissue
》 Dense connective tissue
》 Cartilage
》 Bone
》 Blood
63
What does the areolar connective tissue do?
Areolar connective tissue forms a continuous layer beneath the skin and loosely connects the skin to the underlying muscles. It also serves as a packing tissue that fills the space between organs, blood vessels, nerves and muscles
64
List the basic structure of the areolar connective tissue
◇ The matrix is jelly-like
◇ The types of fibres are found in the matrix:
• yellow, elastic fibres (branched)
• white, inelastic collagen fibres (parallel)
◇ Different types of cells are dispersed, scattered throughout the matrix, ie: fibroblasts, macrophages, fat cells and lymphocytes
65
What are the functions of the areolar connective tissue?
○ Serves as an insulating material — prevents heat loss
○ Protects the organs by serving as packing tissue; eg, around the kidneys
66
What is adipose/ fat tissue?
Adipose or fat tissues are when large amounts of fat is stored in the areolar connective tissue
67
What does the dense connective tissue do?
Dense connective tissue joins muscles to bone (tendons) and bone to bone (ligaments) in our joints
68
List the basic structure of the dense connective tissue
》 Dense connective tissue consists of a small amount if matrix and a small number of cells
》 It does, however, contain a large number of fibres that run more or less parallel to one another
》 When the largest number of fibres are white, inelastic fibres, the connective tissue is known as a tendon
》 When the largest number of fibres are yellow, inelastic fibres, the connective tissue is known as a ligament
69
What are the functions of the dense connective tissue?
▪︎ Inelastic tendons join muscle to bone—they relay muscle contraction and relaxation to the bone so that movement can take place
▪︎ Elastic ligaments join bone to bone—these permit a degree of movement in the joints
70
What is cartilage?
Cartilage is a tough, elastic connective tissue that forms part of the endoskeleton of vertebrates
71
List the three types of cartilage
■ Hyaline cartilage
■ Fibrous cartilage
■ Elastic cartilage
72
Where can you find cartilage?
Cartilage occurs between bones
73
What does cartilage do?
Cartilage lines joints, forms permanent structures; ie: the pinna and the tip of the nose, as well as C-shaped rings in the trachea
74
List the basic structure of the cartilage
¤ It has a tough rubbery matrix that mainly consist of the protein, chondrin
¤ In the matrix are fluid-filled spaces called lacunae
¤ In the lacunae are cartilage cells (chondrocytes) that occur alone, in pairs or in groups of four
¤ On the outside, cartilage is enclosed by a fibrous membrane, called the perichondrium
75
What are the chondrocytes responsible for?
The chondrocytes are responsible for the secretion of the matrix
76
What are the functions of cartilage?
♡ It connects bones to each other, ie; the ribs to the breastbone
♡ It makes joint sockets (joint cavities) deeper to prevent dislocation without hindering movement
♡ It acts as a shock absorber between vertebrae
♡ It forms permanent structures; ie: the pinna and nose
♡ It prevents friction in bones
♡ It keeps tubes open, eg: C-shaped cartilaginous rings in the trachea
77
Where is the bone tissue
Bone tissues occur in various bones of the endoskeleton of vertebrates
78
List the basic structure of bones
☆ Bones contains a hard matrix of calcium phosphate and calcium carbonate
☆ Longitudinal canals, known as Haversian canals, occur in bone tissue and 2
☆ Haversian canals contain blood vessels, nerves and lymphatic vessels
☆ Around the canals, the bone tissue is arranged in concentric layers, the lamellae
☆ In the lamellae are many fluid-filled spaces, the lacunae
☆ Each lacuna contains a bone cell (osteocyte)
☆ Lacunae and lamellae are connected to one another by small canals, the canaliculi
☆ On the outside, bone is enclosed by a fibrous membrane, the periosteum
79
What are the functions of bone tissue?
▪︎ Bone is a supporting framework that gives shape and rigidity to the body
▪︎ It protects delicate organs, such as the brain, spinal chord, heart and lungs
▪︎ It serves as a place of attachment for the muscle to make movement possible
▪︎ Blood corpuscles are manufactured in the bone marrow
▪︎ Minerals, ie; calcium, are stored in the bone tissue
80
Where is blood located?
Blood circulates the blood vessels of the blood system; ie: the arteries, capillary vessels and veins
81
What is the basic structure of blood?
○ The matrix, known as blood plasma, is a watery yellow fluid
○ There are 3 types of blood cells in the blood plasma:
- Red blood corpuscles (erythrocytes)
- White blood cells (leucocytes)
- Blood platelets ( thrombocytes)
82
Blood plasma consist of 90% water and 10% dissolved substances. List all the dissolved substances that the blood plasma consists of
□ Glucose
□ Fats
□ Mineral salts
□ Enzymes
□ Antibodies
□ Amino acids
□ Vitamins
□ Hormones
□ Gases (O2 and CO2)
□ Plasma proteins (fibrinogen and albumin)
83
What are the functions of blood plasma?
☆ It transports nutrients from the digestive system to the tissue
☆ It transports waste products from tissues to the excretory organs
☆ It plays a role in regulating blood temperature
☆ It transports hormones to their target organs
☆ Plasma proteins (eg: fibrinogen) play a role in blood clotting (coagulation)
84
List all the known facts about the red blood corpuscles
○ Red blood corpusles are small disc shaped cells that do not contain nuclei
○ They are biconcave (indented on both sides), which increases the surface area for oxygen absorption
○ They are soft and pliable and are enclosed by a thin, elastic membrane
○ They can be pressed flat in order to move through a capillary and the slower movement allows time for the absorption of oxygen
○They contain iron-containing protein, haemoglobin, which:
▪︎ Binds with O2 or CO2 and acts as a carrier molecules for the gases in the blood
▪︎ Gives blood it's red colour
85
What are the functions of red blood corpuscles?
○ Red blood corpuscles transport oxygen as oxyhaemoglobin from the lungs to the tissue
○ They transport carbon dioxide in carbaminohaemoglobin from the tissues to the lungs
86
List all the known facts about white blood cells (leucocytes)
□ White blood cells are larger than the red blood corpuscles
□ They do not have a fixed shape
□ They are slightly transparent when virtually colorless
□ They have a nucleus
□ They can move through the walls of capillaries & btwn cells
□ They are two types of white blood cells:
• phagocytes
• lymphocytes
87
What are the functions of white blood cells?
◇ Phagocytes move around and engulf bacteria and substances that are foreign to the body, in this way protecting the body from infection and disease
◇ Lymphocytes produce antibodies that destroy bacteria and virus
88
What are blood platelets (thrombocytes)
Blood platelets are flat discs that do not contain cell nuclei
89
What is the function of blood platelets?
They play a role in blood clotting damaged blood vessels
90
What are the three types of muscle tissues?
○ Striated muscle tissue
○ Smooth muscle tissue
○ Cardiac muscle tissue
91
List the basic structure of the striated muscle tissue
• Skeleton muscles are made up of a large number of muscle fibres (muscle cells)
• A muscle fibre is a long, cylindrical cell
• The muscle fibre contains light and dark bonds, hence the name striated
• The content of the muscle fibre consists of a cytoplasm (sarcoplasm), a large number of oval nuclei and a mitochondria
• The cell contents are enclosed by a thin elastic cell membrane, the sarcolemma
• Each muscle fibres consists of thousands of myofils
92
What are the functions of striated muscle tissue?
• Skeletal muscles work in pairs, contacting and relaxing voluntarily, and result in the coordinated movement of specific body parts
93
Where are the smooth muscle tissues found?
Smooth muscle tissues are found in the walls of the alimentary canal, bladder, blood vessels and uterus
94
List the basic structure of the smooth muscle tissue
》 Smooth muscle tissues consist of a Spindle shaped muscle fibre, with one large oval nucleus per fibre
》 The contents of the Smooth muscle fibres also consist of a cytoplasm (sarcoplasm) that is surrounded by a cell membrane (sarcolemma)
95
What are the functions of the Smooth muscle tisse?
◇ Involuntary contraction and relaxation of the Smooth muscle fibres results in slow, rhythmic movements. This ensures that peristalsis takes place in the digestive system
96
Where are the cardiac muscle tissues located?
Cardiac muscle tissue only occurs in the walls of the heart
97
List the basic structure of the cardiac muscle tissue
》 Cardiac muscles consist of branched muscle fibres that are connected to one another by means of muscular (myocardial) bridges. The muscular bridges ensures that the cardiac muscle functions as a unit
》 Fibres are also cross-striated, but only have a single nucleus in the center of each fibre
》 The contents of the muscle fibres also include sarcoplasm, which is enclosed by a thinner sarcolemma
98
What are the functions of cardiac muscle tissues?
☆ Cardiac muscle tissue displays automatism, which causes the uninterrupted, involuntary contraction and relaxation of the heart
99
What are nerve tissues made up of?
Nerve tissues are made up of specialized cells called neurons
100
Where can you find the nerve tissues
Nerve tissues forms the brain and spinal chord and is known as the central nervous system. Nerve tissues outside the central nervous system, which conducts nerve impulses to and from the brain, is known as the peripheral nervous system
101
List the basic structure of the nerve tissue
◇ A typical neuron consists of:
☆A cell body:
▪︎ The cell body has a cell membrane that encloses the cytoplasm
▪︎ In the cytoplasm is a prominent nucleus as well as small, dark bodies called the Nissl granules
☆ Two types of outgrowth extend from the cell body:
▪︎ Dendrites: There can be one or more outgrowths that can conduct nerve impulses to the cell body
▪︎ Axon: This is a single, long outgrowth that conducts nerve impulses away from the cell body. The axon is usually enclosed by a fatty sheath, the myelin sheath, which usually insulates the axon and increases the speed of the nerve impulses
102
List the 3 types of neurons
》 Sensory neurons
》 Motor neurons
》 Interneurons
103
What are sensory neurons?
Sensory neurons are a type of neurons that conduct nerve impulses from the receptors (such as touch receptors, free range nerve endings or sensory organs) to the central nervous system (brain and spinal chord)
104
What are motor neurons?
Motor neurons are a type of neurons that conduct nerve impulses from the central nervous system (brain and spinal chord) to the effector (muscles and glands)
105
What are interneurons?
Interneurons are a type of neurons that conduct nerve impulses between the sensory and motor neurons in the brain and spinal chord
106
What are the functions of the nerve tissue?
☆ Nerve tissue allows an organism to percieve stimuli and respond by transmitting nerve impulses along neurons
