JJ Flashcards
(143 cards)
1
Q
What are the eight characteristics shared by all living organisms?
A
Nutrition, respiration, excretion, response to surroundings, movement, control of internal conditions, reproduction, growth and development.
2
Q
Define ‘nutrition’ in living organisms.
A
The process by which organisms take in and use food for energy, growth, and maintenance.
3
Q
What is ‘respiration’ in biology?
A
A chemical process that releases energy from food, usually using oxygen.
4
Q
What does ‘excretion’ mean?
A
The removal of metabolic waste products from the body.
5
Q
What is meant by ‘response to surroundings’?
A
The ability to detect and react to environmental stimuli.
6
Q
Define ‘movement’ in living organisms.
A
The ability to change position or move parts of the body.
7
Q
What is ‘control of internal conditions’?
A
Maintaining a stable internal environment (homeostasis).
8
Q
Define ‘reproduction’.
A
The process of producing new individuals of the same species.
9
Q
What does ‘growth and development’ refer to?
A
The increase in size and complexity of an organism.
10
Q
What common features do plants show?
A
Multicellular, have chloroplasts, carry out photosynthesis, have cellulose cell walls, store carbohydrates as starch or sucrose.
Examples: maize, peas, beans.
11
Q
What are the key features of animals?
A
Multicellular, no chloroplasts, cannot photosynthesise, no cell walls, usually have nervous coordination, can move, store carbohydrates as glycogen.
Examples: humans (mammals), housefly, mosquito (insects).
12
Q
What are the characteristics of fungi?
A
Not able to photosynthesise, body usually mycelium made of hyphae with many nuclei, some single-celled, cell walls made of chitin, feed by saprotrophic nutrition, may store carbohydrate as glycogen.
Examples: Mucor (hyphal), yeast (single-celled).
13
Q
What are protoctists?
A
Microscopic single-celled organisms. Some are like animals (e.g., Amoeba), others like plants (e.g., Chlorella with chloroplasts). Some cause disease (e.g., Plasmodium causes malaria).
14
Q
What are the common features of bacteria?
A
Microscopic, single-celled, have cell wall, membrane, cytoplasm, plasmids, no nucleus, circular DNA, some photosynthesise, most feed off other organisms.
Examples: Lactobacillus (yoghurt), Pneumococcus (pneumonia).
15
Q
Define ‘pathogen’.
A
An organism that causes disease. Pathogens include fungi, bacteria, protoctists, and viruses.
16
Q
What are viruses?
A
Not living organisms, very small particles, parasitic, reproduce only inside living cells, infect all living organisms, have a protein coat and DNA or RNA, no cellular structure.
Examples: tobacco mosaic virus, influenza, HIV.
17
Q
List the levels of organisation in living organisms.
A
Organelles → cells → tissues → organs → systems.
18
Q
Name the main structures found in cells.
A
Nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes, vacuole.
19
Q
What is the function of the nucleus?
A
Contains genetic material, controls cell activities.
20
Q
What is the function of the cytoplasm?
A
Site of chemical reactions.
21
Q
What is the function of the cell membrane?
A
Controls entry and exit of substances.
22
Q
What is the function of the cell wall (plants, fungi, some bacteria)?
A
Provides support and protection.
23
Q
Function of mitochondria?
A
Site of aerobic respiration and energy production.
24
Q
Function of chloroplasts?
A
Site of photosynthesis (contain chlorophyll).
25
Function of ribosomes?
Site of protein synthesis.
26
Function of vacuole (plants)?
Contains cell sap, maintains cell shape.
27
Similarities and differences between plant and animal cells?
Both have nucleus, cytoplasm, cell membrane, mitochondria, ribosomes. Plant cells also have cell wall, chloroplasts, and vacuole; animal cells do not.
28
What elements are present in carbohydrates, proteins, and lipids?
Carbohydrates: Carbon, hydrogen, oxygen; Proteins: Carbon, hydrogen, oxygen, nitrogen (and sometimes sulfur); Lipids: Carbon, hydrogen, oxygen.
29
What are the basic units of carbohydrates, proteins, and lipids?
Starch/glycogen: made from simple sugars; Proteins: made from amino acids; Lipids: made from fatty acids and glycerol.
30
What is the role of enzymes?
Biological catalysts that speed up metabolic reactions.
31
How does temperature affect enzyme activity?
High temperatures can denature enzymes by changing the shape of the active site, reducing activity.
32
How does pH affect enzyme function?
Extreme pH changes can alter the active site and denature the enzyme.
33
Define diffusion.
The net movement of particles from a high to a low concentration.
34
Define osmosis.
The diffusion of water molecules from a dilute to a concentrated solution through a partially permeable membrane.
35
Define active transport.
The movement of substances against a concentration gradient using energy.
36
What factors affect the rate of movement of substances?
Surface area to volume ratio, distance, temperature, concentration gradient.
37
What is photosynthesis?
The process by which plants convert light energy to chemical energy.
38
Word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen.
39
Symbol equation for photosynthesis?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
40
What factors affect photosynthesis rate?
Carbon dioxide concentration, light intensity, temperature.
41
How is a leaf adapted for photosynthesis?
Large surface area, thin, chloroplasts, stomata, network of veins.
42
Why do plants need mineral ions?
Magnesium for chlorophyll, nitrate ions for amino acids.
43
Components of a balanced human diet?
Carbohydrate, protein, lipid, vitamins, minerals, water, dietary fibre.
44
Functions and sources of key nutrients?
Carbohydrate: energy (bread, pasta); Protein: growth/repair (meat, beans); Lipids: energy/store (butter, oils); Vitamin A: vision (carrots); Vitamin C: healthy tissues (oranges); Vitamin D: bones/teeth (sunlight, dairy); Calcium: bones/teeth (milk); Iron: haemoglobin (red meat); Fibre: digestion (vegetables); Water: all cells (drinks, food).
45
What is peristalsis?
Wave-like muscle contractions that move food through the gut.
46
What are the roles of digestive enzymes?
Amylase/maltase: starch → glucose; Proteases: proteins → amino acids; Lipases: lipids → fatty acids + glycerol.
47
What is the role of bile?
Neutralises stomach acid, emulsifies fats.
48
How is the small intestine adapted for absorption?
Villi increase surface area, thin walls, good blood supply.
49
What is respiration?
The process of releasing energy (ATP) from food molecules.
50
What is ATP?
A molecule that stores and provides energy for cells.
51
Difference between aerobic and anaerobic respiration?
Aerobic uses oxygen, more energy; anaerobic does not use oxygen, less energy.
52
Word equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water (+ energy).
53
Symbol equation for aerobic respiration?
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+ energy).
54
Word equation for anaerobic respiration (animals)?
Glucose → lactic acid (+ energy).
55
Word equation for anaerobic respiration (plants/yeast)?
Glucose → ethanol + carbon dioxide (+ energy).
56
Key structures of the thorax?
Ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli, pleural membranes.
57
Role of intercostal muscles and diaphragm?
They contract and relax to ventilate the lungs.
58
How are alveoli adapted for gas exchange?
Large surface area, thin walls, moist, rich capillary supply.
59
Consequences of smoking?
Lung damage, increased risk of coronary heart disease.
60
Why can unicellular organisms rely on diffusion?
Short distances for substances to move.
61
Why do multicellular organisms need transport systems?
Diffusion alone is too slow for large organisms.
62
Role of phloem?
Transports sucrose and amino acids.
63
Role of xylem?
Transports water and mineral ions.
64
Composition of blood?
Red blood cells, white blood cells, platelets, plasma.
65
Role of plasma?
Transports CO₂, digested food, urea, hormones, heat.
66
Adaptations of red blood cells?
Biconcave shape, no nucleus, haemoglobin.
67
How does the immune system respond to disease?
Phagocytes ingest pathogens; lymphocytes release antibodies.
68
Heart structure and function?
Four chambers; pumps blood around the body.
69
Effects of exercise/adrenaline on heart rate?
Both increase heart rate.
70
Risk factors for coronary heart disease?
Diet, smoking, lack of exercise, genetics.
71
Structure/function of arteries, veins, capillaries?
Arteries: thick walls, carry blood away from heart; Veins: thinner walls, valves, carry blood to heart; Capillaries: very thin walls, exchange substances.
72
Structure of circulation system?
Heart, arteries, veins, capillaries; blood to/from lungs, liver, kidneys.
73
Main excretory products in humans?
Lungs: carbon dioxide; Kidneys: urea; Skin: sweat (water, salts, urea).
74
Origin of waste gases in plants?
Carbon dioxide and oxygen from metabolism, lost through stomata.
75
What is homeostasis?
Maintenance of a constant internal environment.
76
What is required for a coordinated response?
Stimulus, receptor, effector.
77
What are phototropism and geotropism?
Plant growth responses to light (phototropism) and gravity (geotropism).
78
Role of auxin in phototropism?
Promotes cell elongation on shaded side, causes stem to bend toward light.
79
Difference between nervous and hormonal responses?
Nervous: fast, electrical, short-term. Hormonal: slower, chemical, longer-lasting.
80
What is the central nervous system (CNS)?
Brain and spinal cord, linked to sense organs by nerves.
81
How do receptors send signals?
Electrical impulses along nerves into and out of the CNS.
82
Role of neurotransmitters?
Chemicals that transmit signals across synapses.
83
Structure/function of a simple reflex arc?
Receptor → sensory neuron → relay neuron (CNS) → motor neuron → effector (e.g., muscle).
84
Structure/function of the eye?
Detects light, focuses images, enables vision.
85
How does the eye focus?
Lens changes shape (accommodation) for near/distant objects.
86
How does skin regulate temperature?
Sweating, vasoconstriction, vasodilation.
87
Sources/roles/effects of key hormones?
Adrenaline: increases heart rate (adrenal glands); Insulin: lowers blood glucose (pancreas); Testosterone: male secondary sex traits (testes); Oestrogen: female secondary sex traits/menstrual cycle (ovaries); Progesterone: maintains uterus lining (ovaries).
88
Difference between sexual and asexual reproduction?
Sexual involves two parents/gametes, genetic variation. Asexual is one parent, offspring identical.
89
What is fertilisation?
Fusion of male and female gametes to form a zygote.
90
Structure/adaptations of insect- and wind-pollinated flowers?
Insect: colorful petals, scent, nectar, sticky pollen; Wind: small/dull petals, exposed stamens/stigma, light pollen.
91
How does fertilisation lead to seed/fruit formation?
Pollen tube grows to ovule, fertilisation occurs, ovule becomes seed, ovary becomes fruit.
92
How do seeds germinate?
Use food reserves until seedling can photosynthesise.
93
How can plants reproduce asexually?
Natural (runners), artificial (cuttings).
94
Adaptations of human reproductive systems?
Male: sperm production and delivery; Female: egg production, receives sperm, supports embryo.
95
Roles of oestrogen and progesterone?
Oestrogen: builds up uterus lining; Progesterone: maintains lining.
96
Role of placenta?
Supplies nutrients and removes wastes for embryo.
97
How is the embryo protected?
Amniotic fluid cushions it.
98
Roles of oestrogen and testosterone in secondary sexual characteristics?
Oestrogen: breasts, hips, menstrual cycle; Testosterone: facial hair, muscle growth, voice.
99
What is a genome?
The entire DNA of an organism.
100
What is a gene?
A section of DNA that codes for a specific protein.
101
Where are genes located?
On chromosomes in the cell nucleus.
102
What are alleles?
Different versions of the same gene.
103
Define dominant and recessive alleles.
Dominant: always expressed if present. Recessive: only expressed if two copies present.
104
What do 'homozygous' and 'heterozygous' mean?
Homozygous: two same alleles. Heterozygous: two different alleles.
105
Define phenotype and genotype.
Phenotype: physical appearance; Genotype: genetic makeup.
106
What is polygenic inheritance?
Many genes control one trait.
107
What is a monohybrid cross/genetic diagram?
Shows inheritance of a single gene.
108
How to interpret a family pedigree?
Track inheritance of traits across generations.
109
How is sex determined in humans?
XX = female, XY = male.
110
How does mitosis work?
One cell divides to form two identical cells (growth, repair, cloning, asexual reproduction).
111
How does meiosis work?
One cell divides to produce four genetically different gametes with half the chromosome number.
112
What is genetic variation?
Differences in DNA among individuals, caused by mutation, meiosis, and random fertilisation.
113
Human diploid and haploid chromosome numbers?
Diploid: 46 chromosomes; Haploid: 23 chromosomes.
114
What is mutation?
Rare, random change in genetic material; can be inherited.
115
What is Darwin’s theory of evolution by natural selection?
Organisms with advantageous traits survive and reproduce, passing on those traits.
116
How does antibiotic resistance arise in bacteria?
Random mutations give resistance; resistant bacteria survive and multiply, especially with misuse of antibiotics.
117
Define population, community, habitat, and ecosystem.
Population: all individuals of one species in an area
Community: all populations in an area
Habitat: place where an organism lives
Ecosystem: community plus its environment.
118
What factors affect population size/distribution?
Abiotic (non-living, e.g., temperature) and biotic (living, e.g., predators) factors.
119
What are trophic levels?
Producers: make their own food (plants)
Primary consumers: eat producers
Secondary consumers: eat primary consumers
Tertiary consumers: eat secondary consumers
Decomposers: break down dead material.
120
What is a food chain?
Sequence of organisms where each is eaten by the next.
121
What is a food web?
Network of interlinked food chains.
122
What are pyramids of number, biomass, and energy?
Diagrams showing number, mass, or energy at each trophic level.
123
Why is only about 10% of energy transferred between trophic levels?
Most energy is lost as heat, waste, or used in respiration.
124
What are the stages in the carbon cycle?
Photosynthesis, respiration, decomposition, combustion.
125
Biological consequences of air pollution by sulfur dioxide and carbon monoxide?
Acid rain (sulfur dioxide), reduced oxygen transport (carbon monoxide).
126
What are greenhouse gases?
Water vapour, CO₂, nitrous oxide, methane, CFCs.
127
How do human activities contribute to greenhouse gases?
Burning fossil fuels, agriculture, deforestation.
128
What is the enhanced greenhouse effect?
Increased greenhouse gases trap more heat, causing global warming.
129
Biological consequences of water pollution by sewage?
Decreases oxygen in water, kills aquatic life.
130
What is eutrophication?
Excess nutrients cause algal blooms, deplete oxygen, harm aquatic organisms.
131
How do glasshouses/polythene tunnels increase crop yield?
Control environment (temperature, CO₂, light, humidity).
132
How do increased CO₂ and temperature affect crop yield?
Increase rate of photosynthesis, increase yield.
133
Why use fertilisers?
Replace minerals, promote plant growth.
134
Advantages and disadvantages of pesticides and biological control?
Pesticides: effective, but can harm environment
Biological control: environmentally friendly, but may not fully control pests.
135
Role of yeast in food production?
Fermentation in bread making.
136
How is yoghurt made?
Bacteria (Lactobacillus) ferment milk sugars.
137
What is an industrial fermenter?
Vessel for growing microorganisms with controlled conditions.
138
What is selective breeding?
Choosing parents with desired traits to produce offspring with those traits.
139
What is the role of restriction enzymes and ligase?
Restriction enzymes cut DNA at specific sites; ligase joins DNA pieces.
140
What are vectors in genetic engineering?
Plasmids/viruses that carry DNA into cells.
141
How is insulin produced by genetically modified bacteria?
Human insulin gene inserted into bacteria, which produce insulin in fermenters.
142
How are genetically modified plants used?
Improve food production (e.g., pest resistance, higher yield).
143
What does 'transgenic' mean?
An organism that has received genes from a different species.
