biology igcse Flashcards
(132 cards)
1
Q
What does MRS GREN stand for in life processes?
A
Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
2
Q
Define movement in the context of biology.
A
Action by an organism or part of an organism causing a change of position or place.
3
Q
What is respiration?
A
Chemical reactions in cells that break down nutrient molecules and release energy for metabolism.
4
Q
What does sensitivity refer to in living organisms?
A
Ability to detect or sense stimuli in the internal or external environment and to make appropriate responses.
5
Q
How is growth defined in biological terms?
A
Permanent increase in size and dry mass by an increase in cell number, by cell division or cell size or both.
6
Q
What is reproduction?
A
The processes that make more of the same kind of organism.
7
Q
What is excretion?
A
Removal from organisms of the waste products of metabolism, toxic materials, and substances in excess of requirements.
8
Q
What are the waste products of metabolism mentioned?
A
- Heat (via sweating) * Urea (excess nitrogen) * CO2 (excess carbonic acid)
9
Q
Define nutrition in biological terms.
A
Taking in of materials for energy, growth, and development.
10
Q
What do plants need for nutrition?
A
- Light * CO2 * Water * Ions
11
Q
What do animals require for nutrition?
A
- Organic compounds * Ions * Water
12
Q
What type of cell are animals made of?
A
Eukaryote
13
Q
What type of cell are prokaryotes (bacteria) made of?
A
Prokaryote
14
Q
Are fungi unicellular or multicellular?
A
Both unicellular (yeasts) and multicellular (mushrooms).
15
Q
What is the main structure of plant cell walls?
A
Cellulose
16
Q
What is a distinguishing feature of animal cells compared to plant cells?
A
Animal cells lack a cell wall.
17
Q
What do bacteria have that allows some to swim?
A
Flagellum
18
Q
What is the primary function of enzymes?
A
Biological catalysts that speed up chemical reactions without being chemically changed.
19
Q
What is diffusion?
A
Net passive movement of particles from a higher concentration region to a lower concentration region.
20
Q
What factors affect the rate of diffusion?
A
- Concentration gradient * SA:V ratio * Distance * Temperature
21
Q
Define osmosis.
A
Net passive movement of water molecules down their water potential gradient through a partially permeable membrane.
22
Q
What is active transport?
A
Movement of particles through a cell membrane against their concentration gradient using energy from respiration.
23
Q
What is a balanced diet?
A
A diet that includes all nutrients in their correct proportions to maintain health.
24
Q
What are the main chemical elements present in carbohydrates?
A
Carbon, Hydrogen, and Oxygen.
25
What is the polymer of carbohydrates that acts as energy storage in plants?
Starch
26
What is the structure of proteins?
Polymers made from 20 different amino acids.
27
What test can be used to identify the presence of starch?
Add a few drops of Iodine solution; if starch is present, it turns blue/black.
28
What are the associated deficiencies of Vitamin A and Vitamin C?
* Vitamin A: Night Blindness * Vitamin C: Scurvy
29
What is peristalsis?
Waves of contraction of circular muscles that push food along the gut.
30
What is mechanical digestion?
The breaking down of food into smaller pieces without chemically changing them.
31
What is chemical digestion?
The breaking down of large insoluble molecules into smaller soluble molecules.
32
Define absorption in the digestive process.
Movement of small food molecules and ions through the wall of the intestine into the blood.
33
What is assimilation?
Movement of digested food molecules into the cells of the body where they are used.
34
What is egestion?
The passing out of undigested food as faeces through the anus.
35
What is the process that pushes food along the gut?
Contraction of circular muscles behind the food and relaxation of circular muscles in front of the food
36
What are the types of digestive enzymes?
Carbohydrases, Proteases, Lipases
37
What is the function of Amylase?
Starch → maltose
38
Where does maltase act on the gut?
Small intestine
39
What is the main action of Pepsin?
Proteins → amino acids
40
Where is Lipase produced?
Pancreas
41
What adaptations does the small intestine have for its function?
* Villi and microvilli increase surface area
* Folds reduce distance
* Constant blood supply maintains concentration gradient
42
Define homeostasis.
Maintaining the internal conditions constant
43
What is osmoregulation?
Regulation of water
44
What is thermoregulation?
Regulation of temperature
45
What are the organs of excretion?
* Lungs
* Kidneys
* Skin
46
What do the kidneys filter to produce?
Urine
47
What is the main nitrogen-containing waste product filtered by the kidneys?
Urea
48
What happens to excess amino acids in the liver?
Converted into carbohydrates and stored as glycogen
49
What is the effect of hair erector muscles in a cold environment?
Contract to trap a layer of air for insulation
50
What is the effect of adrenaline on heart rate?
Increases heart rate
51
What is aerobic respiration?
Glucose + oxygen → carbon dioxide + water (+energy)
52
What is anaerobic respiration in muscle cells?
Glucose → lactic acid
53
What is EPOC?
Excess Post-exercise Oxygen Consumption
54
What is the purpose of EPOC?
To oxidise lactic acid into CO2 and H2O, maintaining body temperature and removing excess CO2
55
Describe the inhalation process.
* External intercostal muscles contract
* Diaphragm contracts and flattens
* Ribs move up and out
* Volume in thorax increases
* Air pressure in lungs decreases
56
What is the composition of air breathed in?
* O2: 21%
* CO2: 0.04%
57
What adaptations do alveoli have for gas exchange?
* Many alveoli increase surface area
* One cell thick reduces distance for diffusion
* Moist surface dissolves gases better
58
What is the function of goblet cells?
Produce mucus to trap dust and microorganisms
59
What is a consequence of tar in tobacco?
Causes lung cancer and bronchitis
60
What is the role of red blood cells?
* Transport oxygen
* Contain haemoglobin
61
What do phagocytes do?
Engulf pathogens and digest them using enzymes
62
What is the function of lymphocytes?
Produce antibodies specific to antigens
63
What is the central nervous system comprised of?
Brain and spinal cord
64
What is the role of sensory neurons?
Connects to sensors and transmits impulses to the CNS
65
What is the function of the ciliary muscles in the eye?
Control the shape of the lens for focusing
66
What occurs at a synapse?
* Electrical impulse arrives at terminal axon
* Neurotransmitters are released into the synaptic cleft
67
What does the endocrine system do?
Produces hormones to alter activity in target organs
68
What is the process by which neurotransmitters cross the synaptic cleft?
Diffusion
69
What happens when neurotransmitters bind to receptors in the postsynaptic neuron?
A new electrical impulse is created
70
What is the role of receptors in the presynaptic neuron regarding neurotransmitters?
They break down remaining neurotransmitters
71
Define hormone.
Chemical substance produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
72
What type of signal is used in nervous control?
Electrical impulse
73
What type of signal is used in hormonal control?
Hormones
74
How is the transmission of signals achieved in the nervous system?
Through nerves/neurons
75
What is the effect of hormonal control?
Widespread effect (multiple organs at a time)
76
What is the speed of response for nervous control?
Very rapid
77
What is the duration of response for hormonal control?
Long-lasting (until hormone is broken down)
78
What hormone does the thyroid gland produce?
Thyroxine
79
What is the function of insulin?
Lowers blood glucose
80
What is the function of glucagon?
Raises blood glucose
81
What is the function of adrenaline?
Prepares the body for physical activity
82
What does testosterone control in males?
Development of male secondary sexual characteristics
83
What does oestrogen regulate in females?
Menstrual cycle and development of female secondary sexual characteristics
84
What physiological changes occur due to adrenaline release?
* Breathing rate increases
* Heart rate increases
* Mental awareness is increased
85
Define reproduction.
Process of making more of the same kind of organism
86
What is a key characteristic of asexual reproduction?
One parental cell needed
87
What is a key characteristic of sexual reproduction?
Involves gametes
88
What is fertilisation?
The fusion of the nuclei from a male gamete and a female gamete
89
What is ovulation?
The release of an egg cell from the ovary into the oviduct
90
What type of cell division makes gametes?
Meiosis
91
What is mitosis?
Cell division that makes genetically identical cells
92
What is the function of the placenta?
Exchange of substances between the blood of the mother and the blood of the embryo
93
How is the placenta adapted to its function?
* Increased surface area (folded)
* One cell thick (distance)
* Constant blood supply (concentration gradient)
94
What are secondary sexual characteristics in boys during puberty?
* Penis develops
* Growth spurt
* Voice deepens
* Facial hair grows
* Body/pubic hair grows
95
What are secondary sexual characteristics in girls during puberty?
* Menstruation starts
* Hips become rounder
* Breasts develop
96
What is chlorophyll's role in photosynthesis?
Absorbs sunlight
97
What happens to a plant when it is destarched?
Starch is used up for respiration
98
What indicates the presence of starch in a leaf after iodine test?
Blue/black color
99
What are the three factors necessary for good germination?
* Water
* Oxygen
* Warmth
100
What is eutrophication?
A process where an aquatic habitat receives large amounts of minerals
101
What is the consequence of untreated sewage in water systems?
Contains pathogenic bacteria, which are a danger to human health
102
What are the two main types of pest control?
* Chemical (pesticides)
* Biological (natural predators)
103
What is the definition of biomass?
Total amount of living material in an organism
104
What is the function of xylem?
Transport water and minerals
105
What is the function of phloem?
Transport products of photosynthesis
106
What is the difference between homozygous and heterozygous?
Homozygous: same alleles; Heterozygous: different alleles
107
What does genotype refer to?
Describes the alleles each cell has for certain features
108
What does phenotype refer to?
Feature which results from the genotype
109
What is auxin?
A chemical hormone which causes responses to stimuli
110
What is the definition of genotype?
The genetic constitution of an organism
111
What is the first step to determining the offspring genotype from parents?
Look out the gametes of both parents
112
What should you create to visualize the gametes of both parents?
A table with both father and mother gametes at both sides
113
What are the possible genotypes you can determine from the percentage of offspring?
* TT
* Tt
* tt
114
What does it mean if a genotype is true breeding?
It consistently produces the same phenotype in offspring
115
What terms describe the genetic makeup of an organism?
* Homozygous
* Heterozygous
* Recessive
* Dominant
116
How does auxin respond to light?
Auxin goes towards light
117
What effect does gravity have on auxin in plant roots?
Gravity pulls the auxin down so the root goes straight down
118
Where are auxins produced in a plant?
At the tip of the root
119
What is the term for a change in the gene sequence?
Mutation
120
What is the process of natural selection?
Beneficial mutations increase reproductive success and become the norm over generations
121
What are some desirable characteristics in selective breeding for plants?
* Colorful
* Taste
* Bright
* Smell
* Resistant to disease or insects
* Water resistant
* Resistant to cold and heat
122
What are some desirable characteristics in selective breeding for animals?
* Resistant to disease or insects
* Resistant to heat or cold
* Produce milk, cheese, etc.
* Taste
* Smell
123
What is the first step in genetic engineering of insulin?
Extract the DNA from some human cells
124
What enzyme is used to cut the insulin gene out of the DNA?
Restriction enzyme
125
What is a plasmid?
An extra-chromosomal DNA molecule capable of replicating independently
126
What are restriction enzymes?
Enzymes that cut DNA molecules at specific sites
127
What is a vector in genetic engineering?
The means of transferring the gene
128
What is the function of ligase in genetic engineering?
To join cut ends of DNA molecules
129
How do fungi obtain their nutrition?
Saprotrophic Nutrition
130
How do yeast reproduce?
Asexually
131
Fill in the blank: Add 1 packet of yeast to 500cm3 of warm water and _______.
3 spatulas of sugar
132
What should you do after adding yeast and water solution in the yeast reproduction method?
Stir the spatula until mixed, cover with cellophane, and leave it at desired temperature
