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BIOLOGY iGCSE > Section 1 - Nature and Variety of Organisms > Flashcards

Section 1 - Nature and Variety of Organisms Flashcards

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1
Q

what are the characteristics of living organisms

A

Movement
Respiration
Sensitivity

Growth
Reproduction
Excretion
Nutrition
Control internal conditions (homeostasis)

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2
Q

? what is a tissue

A

group of similar cells workig together to carry out a particular fuction

example - xylem tissue, pholem tissue

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3
Q

? what is an organ

A

group of different tissues working together to carry out a function

example - lungs, leaves

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4
Q

? what is an organ system

A

a group of organs working together to form an organ system

example - digestive system (includes stomach, intestines, pancreas and liver)

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5
Q

? eukaryotic

A

HAVE A NUCLEUS

  • complex, include all animal and plant cells
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6
Q

? prokaryotic

A

DO NOT HAVE A NUCLEUS

  • small and simple, eg. bacteria
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7
Q

? what is an organelle

A

tiny structures within cells that can only be seen with a powerfull microscope

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8
Q

? what is a nucleus

A

an organelle containing the genetic material that controls the cells activities. It is surrounded by its own membrane

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9
Q

? what is cell membrane fuction

A

a membrane forming the OUTER surface of the cell and controls the substances that go in and out.

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10
Q

? what is cytoplasm

A

gel-like substance where most of the cell’s chemical reactions happen. contain enzymes that control these reactions

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11
Q

? what are mitochondria

A

small organelles where most of the reactions for aerobic respiration take place. respiration transferes energy that cells need to work

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12
Q

? what are ribosomes

A

small organelle where protein are made in the cell

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13
Q

? what are chloroplasts function

A

photosynthesis, which makes food for the plant, happens here. contain green substance called chlorophyll, also used in photosynthesis.

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14
Q

? what is cell wall and function

A

a rigid sturcture made of cellulose that surrounds the cell membrane.
supports and strengthens cell

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15
Q

? what is vacuole and function

A

large organelle containing cell sap (weak solution of sugars and salts)
and helps support cell

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16
Q

organelles found in typical animal cell

A

nucleus
cell membrane
cytoplasm
mitochondria
ribosomes

17
Q

organelles found in typical plant cell

A

(all of animal organelles:
nucleus
cell membrane
cytoplasm
mitochondria
ribosomes)
choloroplasts
vacuole
cell wall

18
Q

Features of Plants (7)

A
  • multicellular (eukaryotic)
  • chloroplasts (able to carry out photosynthesis)
  • cell walls (made of cellulose)
  • store carbohydrates as sucrose or starch

examples:
flowering plants such as:
- cereal (maize)
- herbaceous legumes (beans and peas)

19
Q

Features of Animals (8)

A
  • multicellular (eukaryotic)
  • no chloroplasts (no photosynthesis)
  • no cell walls
  • nervous coordination so they can respond rapidly to changes in the environment.
  • able to move from one place to another
  • often store carbohydrates as glycogen
20
Q

Features of Fungi

A
  • some are single celled (eukaryotic)
  • others have mycelium body made of hyphae (thread like sturctures that cotai lots of nuclei)
  • no photosynthesis
  • chitin cell walls
  • most use saprotrophic nutrition (secrete extra cellular enzymes into area outside body to disolve food so they can absorb nutrients
  • store carohydrates as glycogen

examples:
yeast (single-celled)
mucor (multicellular ad with mycelium and hyphae)

21
Q

Features of protoctists

A
  • single-celled and microscopic (eukaryotic)
  • some have choloroplasts and are similar to plant cells
  • others are more like animal cells

examples:
- chlorella (plant-like)
- amobea (animal-like)

22
Q

Features of Bacteria

A

-single celled and microscopic
- no nucleus (prokaryotic)
- circular chormosone of DNA
- some can photosynthesise
- most feed of other organisms (living or dead)

examples:
-Lactobacillus bulgaricus (rod-shaped, for yogurt)
-pneumococcus (spherical in shape)

23
Q

Features of Viruses

A
  • particles rather than cells and smaller than bacteria
  • can only reproduce inside living cells
  • parasite - depends on other organisms to grow and reproduce
  • infect all types of living organisms
  • come in many sizes and shapes
  • no cellular sturcture (protein coat around genetic material which is either DNA or RNA)

examples:
- influenza virus
- tabaco mosaic virus
- HIV

24
Q

Pathogens(+ examepl)

A

-organisms that cause disease
- include fungi, protoctists, bacteria and viruses (even though they are not living organisms)

examples:
protoctist - plasmodium - causes malaria
bacterium- pneumococcus - causes pneumonia
viruses - influenza virus - causes flu
- HIV - causes AIDS

25
Q

what are catalysts

A

-a substance that increases the speed of a reaction without being changed or used up by the reaction

26
Q

Enzymes

A
  • living things produce enzymes that act as biological catalysts
  • they reduce the need for high temperatures that might damage cells
  • there are only enzymes to speed up useful chemical reactions (metabolic reactions)
  • ENZYMES ARE PROTEINS made of amino acid chains that fold into unique shapes specific to their function
27
Q

enzymes and active sites

A
  • ENZYMES ARE PROTEINS made of amino acid chains that fold into unique shapes specific to their function
  • every enzyme has an active site - a part where the substrate joins onto the enzyme
  • enzymes are specific to their substrate as the active site is adapted to the substrate shape so no other can fit (lock and key model)
28
Q

what is a substrate?

A

a molecule changed in a reaction

29
Q

Factors affecting enzyme function

A

TEMPERATURE

  • changes rate of enzyme-catalyzed reaction
    AT FIRST : temp increases rate as enzymes have more energy and move about more and are more likely to collide to form enzyme-substrate complexes
    HOWEVER: if too hot, bonds holding together enzyme break, deforming the active site shape and denaturing the enzyme (substrate cant dit)

PH:
if the ph is too high or low it affects bonds, changing active site shape and denatuing the enzyme

All enzymes have an optimum temp and ph (usualy ph 7) in which they work best.

30
Q

Diffusion defenition

A

the net movement of particles from an area of higher concentration to an area of lower concentration

(particles move down a concentration gradient)

31
Q

Diffusion proccess

A
  • doesn’t require energy
  • happens in liquids and gasses
  • bigger the difference in concentration, the faster the diffusion rate
32
Q

cell membranes and diffusion

A
  • substances can move in and out of cells by diffusion, osmosis and active transport
  • only small molecules like glucose, amino acids, water, and oxygen can diffuse through, big molecules like starch and proteins cant fit
  • behaves just like in air with a concentration gradient. they move about randomly so they go both waves but the net (overall) movement is to the area of lower concentration
33
Q

Osmosis definition

A

the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

34
Q

what is a partially permeable membrane

A

a membrane with very small holes in it, so only timi molecules (like water) can go through
example:
cell membrane

35
Q

water around the body with osmosis

A
  • water moves into and out of cells by osmosis
  • tissue fluid surrounds the cells in the body. it is squeezed out of blood capillaries to supply cells
  • tissue fluid has different concentration to fluid inside the cell, so water will either move into or out of the cell by osmosis
  • if a cell is short of water then the solution inside is more concentrated, and the outside is dilute, so the water will move in by osmosis to even out the concentration gradient
  • if a cell has lots o water the solution inside will be more dilute and water will be drawn out of cell and into fluid by osmosis
36
Q

active transport defenition

A

the movement of particles against a concentration gradient (from area of lower concentration to area of higher) using energy released from respirTION

37
Q

active transport examples

A

allows for nutrients to be taken into the blood despite the fact that concentration gradient is the wrong way. this stops us from starving

in plants, it is used to get minerals from the soil (lower concentration) into the root hair cells (higher concentration)

38
Q

Four factors affecting the movement of substances (RATE)

A

1) SURFACE AREA TO VOLUME RATIO - the rate of diffusion, osmosis, and active transport is higher in cells with a larger surface area to volume ratio
2) DISTANCE - short distance means substances move in and out faster (example- cell membranes are really thin)
3) TEMPERATURE - as temperature increases substances move in and out of cells faster
4) CONCENTRATION GRADIENT - substances move in and out of a cell faster if there is a big difference in concentration between the inside and outside of the cell. this doesn’t affect active transport

BIOLOGY iGCSE (12 decks)

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