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cell Flashcards

1
Q

what is a cell

A

the cell is the fundamental structural and functional unit of all living beings, it is the smallest part of the body of an organism which is capable of independent existence and of performing the essential functions of life

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2
Q

after how many days does a red blood cell die

A

about 120 days

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3
Q

what does cell theory state

A

the cell is the smallest unit of structure of all living things, the cell is the unit of function of all living beings, all cells arise from pre-existing cells

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4
Q

what are single celled organisms

A

many small plants and animals are made up of just one cell

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5
Q

give examples of single-celled organisms

A

bacteria, yeast, amoeba

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6
Q

what are few-celled organisms

A

some very small planta and animals are made up of a relatively fewer number of cells- just a few hundred or a few thousand cells

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7
Q

give examples of few-celled organisms

A

spirogyra, volvox

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8
Q

what are multi-celled organisms

A

most plants and animals we see around us including ourselves, are made up of millions and billions of cells

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9
Q

give examples of multi-celled organisms

A

human beings, mango trees

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10
Q

how many cells are in the human body

A

37.2 trillion cells

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11
Q

how many nerve cells are in the human brain

A

100 billion

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12
Q

how many red blood cells per cubic milimetre of blood

A

4-6 million

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13
Q

how many wbc per cubic milimetre of blood

A

7000

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14
Q

what is the smallest cell and its size

A

bacteria (0.3- 5.0 micrometre)

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15
Q

what is the smallest cell in the human body and its size

A

red blood cells (around 7 micrometre)

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16
Q

what are the longest cells

A

nerve cell, extends from tip of finger to the spinal cord

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17
Q

what are the largest cells

A

ostrich egg (before development begins in it) is the largest single cell of the living world today.

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18
Q

why do cells generally remain small

A

this is because
. Different regions of a call can communicate with each other rapidly for the cell to function effectively
. Cells have a large surface area/volume ratio for greater diffusion of substances in and out of the cell

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19
Q

why do cells have a larger surface area relative to volume of the cell

A

they have this to ensure greater diffusion of
.nutrients into the cell
.metabolic wastes from the interior to the outside of the cell
.respiratory gases i.e oxygen into the cell and carbon dioxide out of the cell
.any damage to the cell can be easily repaired

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20
Q

why do cells vary in shape

A

to fit the function it performs

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21
Q

why are human red blood cells circular and biconcave

A

to pass through narrow capillaries and transport oxygen

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22
Q

why are white blood cells amoeboid

A

so they can squeeze out through capillary walls

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23
Q

why are nerve cells long

A

to conduct impulses from distant parts of the brain to the body and vice versa

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24
Q

why are muscle cells long and contractile

A

to pull or squeeze the parts

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25
why are guard cells of stomatal pore in the leaves bean shaped
to open and close the pore
26
what is a generalised cell
It is a basic structural plan shown in all cells, it consists of 3 essential parts .cell membrane (plasma membrane) .nucleus .cytoplasm
27
what are organelles
cell organelles are parts of cell which have a definite shape, definite structure and a definite function
28
what are parts of plant and animal cells that are living and not in cytoplasm or nucleus
cell membrane
29
what are parts of plant and animal cells that are non living and not in cytoplasm or nucleus
cell wall
30
what are parts of plant and animal cells that are living and in the cytoplasm
endoplasmic reticulum, mitochondria, golgi apparatus, ribosomes, lysosomes, centrosome, plastids
31
what are parts of plant and animal cells that are non living and in the cytoplasm
granules, vacuoles, fat droplets
32
what are parts of plant and animal cells that are living and in the nucleus
nuclear membrane, nucleoli, chromatin fibres
33
what are parts of plant and animal cells that are non living and in the nucleus
nucleoplasm
34
what are the characteristics of the cell wall
outermost in plant cells, non living and rigid, freely permeable, mainly composed of cellulose
35
what are the functions of cell walls
gives rigidity and shape to the plant cell, allows substances in solution to enter and leave the cell without any hindrance, provides protection
36
what are characteristics of plasma membrance
outermost in animal cells, lies next to cell wall in plant cells, very thin, flexible, living membrane, possesses fine pores, semi-permeable, made up of lipoproteins
37
what are functions of plasma membrance
seperates content of cell from its surroundings, regulates the entry of certain solutes and ions, maintains shape of the cell in animal cells
38
characteristics of cytoplasm
all the parts together inside the plasma membrane excluding nucleus, contains a mixture of water and soluble inorganic and organic compounds and various organelles
39
functions of cytoplasm
different organelles contained in it perform different functions, all metabolic activities occur in it, medium for initial steps of respiration (production of pyruvic acid)
40
characteristics of endoplasmic reticulum
irregular network of double-membraned tubules, it is continuous with the plasma membrane on the outside and the nuclear membrane on the inside, may be smooth or rough
41
functions of endoplasmic reticulum
supportive framework for the cell, synthesis and transport of proteins and fats
42
mitochondria characteristics
various shapes but usually sausage-like, double walled; inner wall thrown into folds (cristae), have their own dna containing several genes, also contain their own ribosomes
43
mitochondria functions
release of energy from pyruvic acid produced in cytoplasm in the form of ATP, seat of cellular aerobic respiration and stores energy, synthesis of respiratory enzymes.
44
list cell jobs
gas exchange, make energy, build molecules, waste removal, homeostasis, build more cells, respond to external environment
45
what is the cell size of most bacteria
1-10 microns
46
what is the cell size of eukaryotic cells
10-100 microns
47
golgi apparatus and dictyosome characteristics
stacks of flattened membrane sacs, consists of tubules (cisternae), vesicles and vacuoles
48
golgi apparatus and dictyosome functions
synthesis and secretion of enzymes, hormonest etc., formation of acrosome of sperm (only in animals and human beings)
49
ribosomes characteristics
small granules either scattered in the cytoplasm or attached to the outside of the endoplasmic reticulum, single walled dense, spherical bodies, composed mainly of RNA
50
ribosomes functions
protein synthesis
51
lysosomes characteristics
membranous sacs budded off from golgi bodies, contain 40 different types of enzymes
52
lysosomes functions
intracellular digestion, destroy foreign substances, when cell is old or injured, these rapidly destroy organelles (hence called suicide bags), digest cartilages during formation of bones
53
centrosome characteristics
a region surrounding the centrioles, located near the nucleus contains one or 2 centrioles centrioles are surrounded by radiating microtubules to form a "star" (aster) during cell division
54
centrosome functions
initiates and regulates cell division, forms spindle fibres, with help of asters
55
plastid characteristics
several kinds, most common ones are chloroplasts containing the green pigment chlorophyll double membraned, proteinaceous matrix, contain DNA disc like structures called thylakoids contain chlorophyll
56
plastid functions
chromoplasts impart colour to flowers and fruits- (xanthophyll: yellow, carotene: orange, red which help in pollination of the flower and dispersal of seeds chloroplasts (green) trap solar energy for photosynthesis contain the pigment chlorophyll leucoplast stores starch
57
nucleus structure
largest cell organelle mostly spherical and dense nuclear membrane with pores to allow substances to enter and leave contains network of thread-like structures called chromatin fibres which contain DNA
58
nucleus functions
``` regulates cell functions if removed, the cell dies contains chromosomes (bearer of genes that control hereditary characters) ```
59
nucleolus characteristics
one or more round-shaped substructures present inside the nucleus
60
nucleolus functions
produces ribosomes participates in protein synthesis by forming and storing RNA dictates ribosomes to synthesise proteins
61
chromatin fibres structure
the network in resting stage of the nucleus condenses into chromosomes during cell division made up of dna threads
62
chromatin fibres function
chromosomes carry hereditary information or the genes from parents to offsprings
63
vacuoles structure
clear spaces with water or other substances in solution. plant cells have larger vacuoles while animal cells have smaller ones covered by a covering called tonoplast
64
vacuoles function
store water and other substances like food and waste products give turgidity to the plant cells by pressing against the cell wall contain pigments like anthocyanins etc.
65
granules characteristic
small particles, crystals or droplets
66
granules functions
store starch (in plant cells), glycogen (in animal cells) and fat containing granules which serve as food for the cell
67
state structural differences between plant cell and animal cell
Plant cells have a definite cell wall made up of cellulose while animals cells dont have a cell wall Centrosome is not present in plant cell but is present in animal cell Vacuoles are prominent in plant cells while if there are any vacuoles in animal cells they are small and temporary plant cells usually contain plastids while animal cells dont contain plastids
68
state quantitative differences between plant cell and animal cell
plant cells are usually larger with distinct outlines while animal cells are usually smaller with less distinct boundaries plant cells have a less dense cytoplasm while animal cells have a denser and more granular cytoplasm Plant cells have only a thin lining of cytoplasm while in animal cells cytoplasm fills almost the entire cell
69
state differences between prokaryotic and eukaryotic cells
nucleus is not well defined in prokaryotic cells while eukaryotic cells have well defined nucleus with a nuclear membrane prokaryotic cells have a single length of only DNA while eukaryotic cells have several lengths of genetic material (chromosomes) containing DNA wound around certain proteins prokaryotic cells have small ribosomes while eukaryotic cells have larger ribosomes prokaryotic cells have no other cell organelles while eukaryotic cells have several organelles like mitochondria, endoplasmic reticulum, chloroplasts etc.
70
give examples of prokaryotic cell
bacteria, blue green algae (cyanobacteria)
71
give example of eukaryotic cell
euglena, amoeba and all plants and animals
72
list cell jobs
gas exchange, make energy, build molecules, waste removal, homeostasis, build more cells, respond to external environment

biology (4 decks)

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