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IGCSEs by Thili > 🍄 | Unit 1 & 2 | Characteristics, Classification and Organization of Living Organisms > Flashcards

🍄 | Unit 1 & 2 | Characteristics, Classification and Organization of Living Organisms Flashcards

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1
Q

What do animals need for nutrition?

A

Animals require organic compounds, ions and usually water

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2
Q

How are organisms usually classified?

A

Organisms can be classified into groups by the features that they share

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3
Q

What happens when the species get more and more subdivided?

A

The species in these groups have more and more features in common the more subdivided they get

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4
Q

What is the sequence of classification?

A

Kingdom, Phylum, Class, Order, Family, Genus, Species

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5
Q

Why do organisms share features?

A

Organisms have features in common because they originally descend from a common ancestor

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6
Q

How were organisms classified originally?

A

They were classified using morphology and anatomy

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7
Q

How were organisms classified as technology advanced?

A

As technology advanced, organisms were classified using microscopes, knowledge of biochemistry and DNA sequencing, which allowed us to classify organisms in a more scientific approach

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8
Q

What did studies of DNA sequences of different species show?

A

Studies of DNA sequencing of different species showed that the more similar the base sequences in the DNA of two species are, the more closely related they are

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9
Q

What are DNA sequences used to code for?

A

DNA sequences are used to code for amino acid sequences in proteins

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10
Q

Can amino acid sequences be used to determine how closely related organisms are?

A

Yes, amino acid sequences can also be used to determine how closely related organisms are

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11
Q

Why aren’t viruses a part of any classification system?

A

Viruses are not part of any classification system because they are not considered living things

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12
Q

Do viruses carry out the seven life processes?

A

No, viruses do not carry out the seven life processes. Instead, they take over the host cell’s metabolic pathways to make multiple copies of themselves

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13
Q

What is the structure of a virus?

A

A virus structure is genetic material (DNA or RNA) inside a protein coat

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14
Q

The cells of all organisms contain…

A
  • cytoplasm
  • DNA as genetic material (either in the nucleus or spread around the cytoplasm)
  • a cell membrane
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15
Q

When observed under an electron microscope, all cells also contain…

A

…ribosomes for protein synthesis, and enzymes for respiration (enzymes are usually found in mitochondria)

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16
Q

The five kingdoms organisms are

A

Animals, Plants, Fungi, Protoctists, Prokaryotes

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17
Q

What is saprophytic?

A

Saprophytic means to feed on dead or decaying material

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18
Q

What is parasitic?

A

Parasitic means to feed on live material

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19
Q

What two categories can animals be split into?

A

Vertebrates and invertebrates

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20
Q

What is a common feature of vertebrates?

A

All vertebrates have a backbone

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21
Q

Classes of vertebrates

A

Mammals, birds, amphibians, reptiles and fish

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22
Q

Main features of mammals

A

• have fur/hair on skin
• have a placenta
• young feed from mammary glands
• have external ears
• endothermic

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23
Q

Main features of birds

A

• have feathers on skin
• lay eggs with hard shells on land
• have two wings and two legs instead of forelimbs
• have a beak
• endothermic

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24
Q

Main features of amphibians

A

• have smooth, moist skin
• lay eggs without shells in water
• adults usually live on land (so they have lungs), larvae live in water (so they have gills)

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25
Main features of reptiles
• have dry, fixed scales on skin • lay eggs with rubbery shells on land
26
Main features of fish
• have loose, wet scales on skin • lay eggs without shells in water • have gills to breathe
27
What is a morphological characteristic used to classify invertebrates?
A morphological characteristic used to classify invertebrates is whether they have legs or not
28
What are Arthropods?
Arthropods are a phylum of invertebrates that have jointed legs
29
Classes of Arthropods
Myriapods, insects, arachnids and crustaceans
30
Main features of myriapods
• body consists of many segments • each segment has at least one pair of jointed legs • one pair of antennae
31
Main features of insects
• 3-part body: head, thorax, abdomen • three pairs of jointed legs • two pairs of wings (either or both pairs are vestigial) • one pair of antennae
32
Main features of arachnids
• 2-part body: cephalothorax and abdomen • four pairs of jointed legs • no antennae
33
Main features of crustaceans
• more than four pairs of jointed legs • chalky exoskeleton made of calcium • two pairs of antennae • breathe through gills
34
The plant kingdom includes organisms such as...
...ferns and flowering plants
35
What is the pigment that plants contain?
At least part of a plant is green because of the presence of the pigment chlorophyll, which absorbs energy from sunlight for the process of photosynthesis
36
What are the leaves of ferns called?
The leaves of ferns are called fronds
37
Do ferns produce flowers?
No, ferns do not produce flowers, instead reproduce by spores produced on the underside of the fronds
38
How do flowering plants reproduce?
Flowering plants reproduce sexually by means of flowers and seeds
39
How are the seeds in flowering plants produced?
The seeds in flowering plants are produced inside the ovary, at the base of the flower
40
Into what groups can flowering plants be divided?
Monocotyledons and dicotyledons
41
Features of monocotyledons
• have a taproot system • flowers' petals are in multiples of three • have parallel leaf veins
42
Features of dicotyledons
• have fibrous roots • flowers contain petals in multiples of four or five • have reticulated leaf veins
43
Where is cytoplasm found?
Cytoplasm is found inside the cell and contains all the other cell structures
44
What is the large nucleus surrounded by?
The large nucleus is surrounded by a nuclear membrane to separate the nucleus from the cytoplasm
45
What is the position of the cell membrane?
The cell membrane surrounds the cell
46
What is the position of the cell wall (in plants)?
The cell wall is made out of cellulose and surrounds the cell membrane in plant cells
47
What are chloroplasts?
Chloroplasts are organelles that are packed with the pigment chlorophyll and so they are green in colour
48
What are vacuoles?
Vacuoles are large vesicles that take up a large part of the interior of a plant cell
49
All cells except for prokaryotic cells contain
mitochondria and ribosomes
50
What are mitochondria?
Mitochondria are organelles that are found throughout the cell (aerobic respiration occurs in mitochondria)
51
What are ribosomes?
Ribosomes are tiny structures that can be free within the cytoplasm or attached to a system of membranes called Rough Endoplasmic Reticulum
52
Functions of nucleus
Nucleus controls cell division and contains genetic material in chromosomes which controls how cells work and grow
53
Functions of cytoplasm
Cytoplasm supports cell structures, is the site of many chemical reactions and contains water and many solutes
54
Functions of cell wall
Cell wall gives the cell extra support and defines its shape
55
Functions of cell membrane
The cell membrane holds the cell together and controls substances entering and leaving the cell
56
Functions of a vacuole
- Contains cell sap - Used for storage of certain materials - Helps support the shape of the cell
57
Functions of chloroplasts
∘ sites of photosynthesis, providing food for plants ∘ chlorophyll pigments absorb the light energy needed for the reaction to happen
58
Functions of mitochondria
Mitochondria are the site of aerobic respiration, providing energy for the cell, and cells with higher rates of metabolism have higher numbers of mitochondria to provide sufficient energy
59
Functions of ribosomes
Ribosomes are the site of protein production in protein synthesis
60
Functions of vesicles
Vesicles are used to safely transport substances from one part of a cell to another
61
What are specialized cells?
Specialized cells are those which have developed certain characteristics to perform particular functions
62
How are these differences in specialized cells controlled?
These differences are controlled by genes in the nucleus
63
How do cells specialize?
Cells specialize by undergoing differentiation
64
What is differentiation?
Differentiation is a process by which cells develop the structure and characteristics needed to be able to carry out their functions
65
Function of ciliated cells
Movement of the mucus in the trachea and bronchi
66
Adaptations of ciliated cells
Extensions of cytoplasm at the surface of the cell form hair-like structures (cilia) which beat to move mucus and trapped particles up to the throat
67
Function of nerve cells
Conduction of impulses
68
Adaptations of nerve cells
∘ long ∘ have extensions and branches ∘ the axon is covered with a fatty sheath
69
Functions of red blood cell
Transport of oxygen
70
Adaptations of red blood cell
- biconcave disc shape - contains haemoglobin - doesn't contain a nucleus
71
Function of sperm cell
Reproduction
72
Adaptations of sperm cell
∘ the head contains genetic material for fertilisation in a haploid nucleus ∘ the acrosome in the head contains digestive enzymes to penetrate an egg ∘ the middle piece is packed with mitochondria ∘ tail enables sperm to swim
73
Function of egg cell
Reproduction
74
Adaptations of egg cell
* haploid nucleus contains genetic material for fertilisation * jelly-like coating that changes after fertilisation so that no more sperm can enter * cytoplasm containing a store of energy which will provide energy for the dividing zygote
75
Function of root hair cell
absorption of water and mineral ions from soil
76
Adaptations of root hair cell
- increased surface area to ensure maximum absorption of water and mineral ions - walls are thin to make sure water moves through quickly - no chloroplasts present
77
Function of xylem vessel
Conduction of water through the plant; support of the plant
78
Adaptations of xylem vessel
- there are no top and bottom walls between xylem vessels so there is a continuous column of water running through them - cells are dead without organelles or cytoplasm to allow free passage of water - their walls become thickened with a substance called lignin, which means that they are able to help support the plant
79
Function of palisade mesophyll cell
Photosynthesis
80
Adaptations of palisade mesophyll cell
- column shaped to maximize absorption of sunlight and fit as many in a layer under the upper epidermis of the leaf as possible - contains many chloroplasts for maximum photosynthesis
81
Organs in a root system
root, tuber
82
organs in the immune system
thymus, spleen
83
organs in the excretory system
liver, kidney, skin, lungs
84
organs in the nervous system
brain, spinal cord
85
organs in the reproductive system
ovary, cervix, vagina, uterus, testes, penis
86
What is the use of a classification system?
Classification systems' goal is to reflect evolutionary relationships between organisms.
87
Why is the axon of a nerve cell covered with a fatty sheath?
To insulate the nerve cell and speed up nerve impulses.
88
Why is the nerve cell long?
So that it can run to and from different parts of the body and the nervous system.
89
Why does the nerve cell have branches and extensions?
The nerve cell has extensions and branches so that it can communicate with other nerve cells, glands and muscles.
90
Why do red blood cells have a biconcave disc shape?
To increase the surface area for more efficient diffusion of oxygen
91
Why do red blood cells have no nucleus?
To increase the amount of space available for haemoglobin inside the cell
92
Why do red blood cells contain haemoglobin?
Red blood cells contain haemoglobin which joins with oxygen to transport it.
93
# **Plant cells** Unicellular or multicellular?
Unicellular
94
# **Animal cells** Unicellular or multicellular?
Multicellular
95
# **Protoctist cells** Unicellular or multicellular?
Unicellular mostly | sometimes multicellular
96
# **Fungal cells** Unicellular or multicellular?
Multicellular
97
# **Prokaryotic cells** Unicellular or multicellular?
Unicellular

IGCSEs by Thili (28 decks)

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