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IGCSE Biology > Cells, Organs and Life Processes > Flashcards

Cells, Organs and Life Processes Flashcards

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1
Q

What organism have bigger surface area?

A
  • smaller organisms
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2
Q

What is a prokaryote?

A
  • another term for bacteria

- meaning ‘before nucleus’

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3
Q

What is an organ system?

A
  • a group of organs working together to perform a particular function
  • e.g. digestive system breaks up food
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4
Q

Name the parts of a bacterium cell

A
  • a cytoplasm
  • a cell membrane surrounded by
  • a cell wall
  • genetic material floats in the cytoplasm because bacterial cells don’t have a distinct nucleus. Some of the genes are found in circular structures called plasmids.
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5
Q

What happens when the water concentration in a tissue fluid is higher than in the cells fluid?

A
  • the tissue fluid is a hypotonic solution

- the water moves into the cell

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6
Q

What is a tissue?

A
  • a group of similar cels that work together to carry out a particular function
  • can include more than one type of cell
  • e.g. muscular tissue, glandular tissue, epithelial tissue
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7
Q

What pressure supports plant tissues?

A
  • turgor pressure
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8
Q

What are some plant tissues?

A
  • epidermal tissue: covers the whole plant
  • palisade mesophyll tissue: where most of the photosynthesis occurs
  • spongy mesophyll tissue: contains big air spaces to allow gases to diffuse in and out of cells
  • xylem and phloem: they transport things like water, mineral ions, sucrose around the plant
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9
Q

What happens if a plant does not get enough water?

A
  • cells lose their turgor pressure, they become flaccid and plants start to wilt
  • if it is really short of water, the cytoplasm inside its cells starts to shrink and the membrane pulls away from the cell wall
  • this is called plasmolysis, and the cell is plasmolysed
  • because of the cell wall, the plant doesn’t completely lose its shape
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10
Q

What is osmosis?

A
  • the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration
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11
Q

Where is the xylem in

1) the root
2) the stem ?

A

the root:

  • one of xylem’s functions is support
  • roots have to resist crushing as they push through the soil
  • xylem is in the centre to give it strength

the stem:

  • stems need to resist bending
  • the xylem forms a sort of ‘scaffolding’
  • phloem is always around the outside of the stem
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12
Q

What happens when the water concentration in a tissue fluid is the same as in the cell fluid?

A
  • the tissue fluid is an isotonic solution

- no net movement

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13
Q

How are villi adapted for food absorption?

A
  • there are millions of villi
  • increase the surface area so food is absurd much more quickly
  • one-cell thick
  • very good blood supply to assist quick absorption
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14
Q

What are palisade leaf cells adapted for and how?

A
  • they are adapted for photosynthesis
  • they are packed with chloroplasts. Most of them are crammed at the top of the cell, so nearer the light
  • tall shape means a large surface area exposed down the side for absorbing CO2 from the air in the leaf.
  • think shape means that a lot can be packed at the top of a leaf
  • they are grouped together at the top of the leaf
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15
Q

What are the organs of plants?

A
  • stems
  • roots
  • leaves
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16
Q

What type of organism is yeast?

A
  • a single-celled organism

- a microorganism

17
Q

What is diffusion?

A
  • the spreading of the particles of any substance in a solution, or particles of a gas, resulting in a net movement from an area of high concentration to an area of low concentration
  • the greater the difference in concentration, the faster the rate of diffusion
18
Q

Give example of active transport

A
  • plants can absorb ions from a very dilute solution, against the concentration gradient, but needs energy from respiration to work
  • taking glucose from low concentrations in the intestines and from low concentration in the kidney tubules
19
Q

How are alveoli adapted for gas exchange?

A
  • there are millions of alveoli to increase the surface area (about 75m^2 in humans)
  • a moist lining for dissolving gases
  • very thin walls, one cell thick
  • a good blood supply
20
Q

What type of organism are bacterial cells?

A
  • a single-celled organism

- a microorganism

21
Q

What happens when a plant is well-watered?

A
  • its cells draw water in by osmosis and becomes swollen
  • they are turgid
  • the contents of the cell push against the inelastic cell wall, called turgor pressure, helping to support the plant tissues
22
Q

How are sperm and egg cells adapted for reproduction?

A
  • the main functions of an egg cell are to carry the female DNA and to nourish the developing embryo in the early stages
  • egg cell contains huge food reserves to feed the embryo
  • when a sperm fuses with the off, the egg’s membrane instantly changes its structure to stop any more sperm getting in, making sure there is the right amount of DNA
  • the function of the sperm is to get male DNA to the female DNA.
  • has a long tails and streamlined head to help it swim to the egg
  • has a lot of mitochondria to provide energy
  • also carries enzymes in their heads to digest through the egg cell membrane
23
Q

Name the parts of a yeast cell

A
  • nucleus (containing genetic material)
  • cytoplasm
  • cell membrane which is surrounded by a
  • cell wall
24
Q

Describe the parts of an animal cell

A
  • nucleus: contains genetic material that controls the activities of the cell
  • cytoplasm: gel-like substance where most of the chemical reactions take place. Contains enzymes that controls these chemical reactions
  • cell membrane: holds the cell together and controls the passage of substances into and out of the cell
  • mitochondria: most of the reactions for respiration take place here; energy is released during respiration
  • ribosomes: where protein synthesis occurs
25
Q

What is a eukaryote?

A
  • cells with a nucleus
26
Q

What substances can move in and out of cells by diffusion?

A
  • dissolved substances
  • e.g. oxygen, required for respiration, glucose, amino acids, waters
  • starch and proteins are too big
27
Q

What is tissue fluid?

A
  • it surrounds the cells in the body
  • contains water, oxygen, glucose etc
  • squeezed out of the blood capillaries to supply the cels with everything they need
28
Q

Describe the parts of a plant cell

A
  • nucleus: contains genetic material that controls the activities of the cell
  • cytoplasm: gel-like substance where most of the chemical reactions take place. Contains enzymes that controls these chemical reactions
  • cell membrane: holds the cell together and controls the passage of substances into and out of the cell
  • mitochondria: most of the reactions for respiration take place here; energy is released during respiration
  • ribosomes: where protein synthesis occurs
  • rigid cell wall: made of cellulose. supports the cell and strengthens it
  • permanent vacuole: contains cell sap, a weak solution of sugar and salts
  • chloroplasts: absorbs light energy during photosynthesis, to make food. Contains a green substance called chlorophyll
29
Q

What are guard cells adapted for and how?

A
  • they have a special kidney shape to open and close the stomata in a leaf to adapt for gas exchange and controlling water loss within a leaf
  • when a plant has lots of water, the guard cells fill with it and become turgid. This opens the stomata so gases can be exchanged for photosynthesis
  • when the plant is short of water, the guard cells lose water and become flaccid, closing the stomata. this stops too much water vapour from escaping
  • thin outer walls and thickened inner walls make the opening and closing work
  • sensitive to light and close at night to save water
  • more stomata on the undersides of leaves than the top since lower surface is shaded and callers, so less water is lost through the stomata than if they were on the upper surface
30
Q

What happens when the water concentration in a tissue fluid is lower than in the cell fluid?

A
  • the tissue fluid is a hypertonic solution

- water moves out of the cell

31
Q

How are red blood cells adapted to carry oxygen?

A
  • concave shapes gives a big surface area for absorbing oxygen. also helps them pass smoothly inside capillaries to reach body cells
  • packed with haemoglobin, the pigment that absorbs oxygen
  • no nucleus, for more room to store haemoglobin
32
Q

What is active transport?

A
  • substances absorbed against a concentration gradient, from a lower to higher concentration
33
Q

What is an organ?

A
  • a group of different tissues that work together to perform a certain function
  • e.g. stomach

IGCSE Biology (16 decks)

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