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Biology Igcse > B1-B4 > Flashcards

B1-B4 Flashcards

1
Q

Define: movement

A

An action by an organism or part of an organism causing a change of position or place

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2
Q

Define respiration

A

the chemical reactions in cells that break down nutrient molecules and release energy for metabolism

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3
Q

Define sensitivity

A

the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses

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4
Q

Define growth

A

a permanent increase in size and dry mass by an increase in cell number or cell size or both

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5
Q

Define reproduction

A

the processes that make more of the same kind of organism

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6
Q

Define excretion

A

removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements

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7
Q

Define nutrition

A

taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and ions; animals need organic compounds and ions and usually water

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8
Q

What are all living organisms made of?

A

Unicellular organisms, such as bacteria consist of a single cell

Multicellular organisms consist of many cells
Ex: humans = approximately 50 trillion cells

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9
Q

Draw and label the parts of a plant cell

A

Cellulose cell wall
Cell membrane
Nucleus
Cytoplasm
Motichondrion
Permanent vacuole
Chloroplast

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10
Q

Draw and label the parts of an animal cell

A

Cytoplasm
Nucleus
Cell membrane
Mitochondrion

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11
Q

Compare plant and animals cells

A

Plant cells -> cellulose cell wall outside the cell membrane
Animal cells -> no cell wall

Plant cells -> chloroplast (with chlorophyll)
Animal cells -> no chloroplast

Plant cells -> large vacuoles with cell sap
Animal cells -> small vacuoles

Plant cells -> starch grains
Animal cells -> no starch grains, sometimes glycogen granules

Plant cells -> regular shape
Animal cells -> irregular shape

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12
Q

What are the functions of the parts of the cell and animal cells?

A

Cell membrane:
Thin layer of protein and fat
Controls what goes in and out of cells
Partially permeable

Cell wall:
Plant cells only
Mainly cellulose (crisscrossed -> strong covering)
Protects and supports cells (no burst)
Fully permeable

Cytoplasm:
Clear jelly (around 70% water)
Many substances dissolved in it -> proteins
Different metabolic processes happen here

Vacuoles:
Space in a cell surround by a membrane, contain a solution
presses out -> keep cell shape
Plant cells -> large and permanent (solution of sugars + other = cell sap)
Animals cells -> smaller

Chloroplast:
Only in plants -> the green pigment (chlorophyll) -> photosynthesis
Often has starch

Nucleus:
Genetic information -> chromosomes -> DNA

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13
Q

What is the location and functions of these cells:
Ciliated cells
Root hair cells
Palisade mesophyll cells
Red blood cells
Sperm and egg cells

A

ciliated cells – in the trachea and bronchi →movement of mucus (carried bad bacteria and goes to stomach where acid destroys)

root hair cells – near the ends of plants roots → absorption

palisade mesophyll cells – beneath the epidermis of the leaf → photosynthesis

red blood cells – in mammal blood → transport of oxygen

sperm and egg cells – in testes and ovaries → reproduction

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14
Q

How is magnification calculated (formula)?

A

Magnification= size of image/size of real object

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15
Q

Define diffusion

A

Movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient as a result of their random movement

Passive processes -> no energy required
Diffuse until equilibrium is reached

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16
Q

What are factors that influence diffusion?

A

Surface area:
Surface area of membrane increase, rate of diffusion increases
More space for molecules to diffuse

Concentration:
Greater the concentration gradient, quicker the diffusion
Greater difference in concentrations

Temperature:
Temp increases, diffusion increases
Particles gain kinetic energy -> diffuse more quickly

Distance:
Shorter distance, faster diffusion
Substance travels less

17
Q

What quality does the membrane have to have to allow diffusion?

A

It is partially permeable

18
Q

Define osmosis

A

Movement of water molecules from region of higher water potential to region of lower water potential through a permeable membrane

19
Q

What is the effect on plant tissue if it is immersed into solutions of different concentration?

A

Low concentration solution (high water potential):
Solution in cell more concentrated than outside cell
Water diffuses for equilibrium
Vacuole is full -> pressing up against cell membrane+wall -> cell is turgid (as it should be)

Equal concentration solution (equilibrium):
Solution outside and inside cell have equal concentration
Cell is flaccid -> plant begins to wilt

High concentration solution (low water potential):
Solution inside cell less concentrated than outside cell
Water diffuses out for equilibrium -> cytoplasm and vacuole shrink -> cell wall left as cytoplasm pulls away -> cell wall is plasmolysed (plasmolysis)

20
Q

What process is necessary for the uptake of water in plants?

A

Osmosis
Soil has water -> water diffused through the cell membranes of root hair cells -> into plant -> photosynthesis + retain turgidity

21
Q

What is the effect on animal cells if it is immersed into solutions of different concentration?

A

Low concentration solution:
Solution outside is less concentrated than inside
Water diffuses in -> no cell wall -> cell ruptures due to excess water -> lysis

Equal concentration solution:
Normal

High concentration solution:
Solution outside is more concentrated than inside
Water diffuses out -> cytoplasm shrinks -> whole cell shrivels -> crenation

22
Q

What is are the chemical elements in carbohydrates?

A

Carbon, hydrogen and oxygen

23
Q

What are carbohydrates? (+bond type)

A

Long chains of simples sugars

Glucose -> simple sugar (monosaccharide -> soluble in water)
2 glucose -> maltose (disaccharide -> soluble in water)
Lots of glucose -> starch, glycogen, cellulose (poly saccharide -> insoluble in water)

Carbohydrates bonds -> glycosidic bonds

24
Q

What is the used of carbohydrates?

A

Easily available energy
Release energy into cells -> respiration
Glucose travels to cells to release energy for metabolic reactions
Storage as starch in plants + cellulose fibers in plant walls

25
Q

What is are the chemical elements of proteins?

A

Carbon, Hydrogen, Oxygen, Nitrogen, small amounts of Sulphur

26
Q

What are proteins? (And type of bond)

A

Long chains of amino acids
20 different types that can be arranged many ways

Amino acids joined by peptide bonds-> protein
Some are soluble (haemoglobin) some are insoluble (keratin)

27
Q

What are the uses of proteins?

A

Making cells
Enzymes
Haemoglobin, keratin, etc.

28
Q

What are the chemical elements of fats/lipids?

A

Carbon, hydrogen, oxygen

29
Q

What are fat/lipids?

A

Triglycerides (1 glycerol, 3 fatty acids)
Insoluble in water

30
Q

What are the uses of fats/lipids?

A

Storage of energy
Insulation
Making cell membranes

31
Q

What test can be preformed to confirm the presence of starch?

A

Iodine solution

Dimple tray -> samples of food (large surface area) -> add one drop of iodine solution

Orange/brown -> negative
Blue/black -> positive

32
Q

What test can be preformed to confirm the presence of reducing sugars?

A

Benedict’s solution

Mash food (high surface area) -> add equal amounts of food and Benedict’s solution -> heat in water bath

Blue -> negative
Green/orange/red -> low/medium/high amounts

33
Q

What test can be preformed to confirm the presence of proteins?

A

Biuret test
Chop food into small pieces (large surface area) -> add biuret solution to food -> shake until you see color

Blue -> positive
Purple -> negative

34
Q

What test can be preformed to confirm the presence of fats and oils?

A

Ethanol emulsion

Chop up food (more surface area) to around 1 cm^3 -> add 2cm^3 of ethanol -> shake -> add 3cm^3 of water (1:2:3 ratio)-> shake

Milky/white -> positive
Clear -> negative
Fat dissolves in ethanol but not water -> fat-ethanol mixture separates from water if fat is present

35
Q

Why is water important for metabolic reaction?

A

Water is a solvent

we are 60% water
All reactants must be dissolved in water for metabolic reactions
For transport all molecules have to be dissolved in water

36
Q

What are enzymes?

A

Biological catalyst that speed up chemical reactions inside all cells -> not used up in the process
Catalyst -> speed up reactions by lowering the activation energy

Occur naturally

Thousands of types, all for different reactions

Enzymes -> proteins

37
Q

Explain enzyme action (complementary shapes)

A

Enzymes -> very specific about which reactions they can catalyze

Molecules have to be exactly the right shape to bind with enzyme + react

Active site (part of enzyme with a specific shape in order to bind to correct substrate/products) need to be the right shape for substrate (reactant) to attach

38
Q

What effects the rate of a enzyme-catalyzed reaction?

A

Temp, pH, enzyme concentration, substrate concentration, surface area, pressure

39
Q

What effect does a change in temp or pH have on an enzyme?

A

change from the optimum (37°C, pH 7-> when enzyme works the fastest) causes the shape of the enzyme to change permanently -> the enzyme is denatured

TEMP
Chemical reactions work faster at high temps -> more likely to collide -> reaction more likely to occur
BUT
Enzymes are damaged by high temps -> for humans around 40°C
- enzymes lose shape, active site no longer fits -> denatured

pH
pH too acidic or alkaline-> denature

REMEMBER: enzymes are chemical not organisms- they are not KILLED but DENATURED

Biology Igcse (11 decks)

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