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Biology Y9 > Cell Division and Exchange > Flashcards

Cell Division and Exchange Flashcards

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1
Q

What is Mitosis

A

Cell division that results in 2 diploid daughter cells that are genetically identical to the parent cell and to each other

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2
Q

What are the functions of Mitosis

A

Growth and development of tissues in multicellular organisms

Repair of tissues in multicellular organisms

Asexual reproduction in multicellular organisms and binary fission (a type of mitosis in bacteria) in unicellular organisms

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3
Q

What is a Cell Cycle

A

Series of stages that a cell goes through when it grows and divides.

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4
Q

What is the Mitosis Cell Cycle

A

G1 - sub-cellular structures duplicate (excluding chromosomes)

S - Each of the 46 chromosomes is duplicated to form 2 copies of each chromosome

G2 - DNA is checked for errors made during replication. Done using enzymes, and any errors can be fixed

Mitosis - the chromosomes move to opposite poles of the cell and 2 nuclei form

Cytokinesis - cytoplasm divides and cell membrane separates creating 2 new cells

G0 - Temporary cell resting. Some cells will never divide again (e.g. nerve cells)

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5
Q

What are the 6 Phases involved in the Cell Cycle

A 
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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6
Q

Interphase

A

G1, S & G2 (makes up about 90% of the cell cycle, the next phases all happen in Mitosis which is only about 10% of the cell cycle)

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7
Q

Prophase

A 
Nuclear membrane disappears
DNA unwinds & condenses into chromosomes (2 sister chromatids held together by a centromere which is a circle in the middle of the 2 chromatids)
Spindle fibres (fibres that will pull the chromatids apart later, the spindle fibres emerge from the centriole) form & become visible
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8
Q

Metaphase

A

The chromosomes line up along the equator of the cell (vertical not horizontal)
Spindle fibres attach to chromosomes at the centromere of the chromatids

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9
Q

Anaphase

A

Sister chromatids are pulled to the edges of the cell (the poles) by the spindle fibres (now there are 2 different chromosomes on each side)

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10
Q

Telophase

A

A nuclear membrane forms around each of the sets of chromosomes separating them from one another and creating 2 nuclei.

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11
Q

Cytokinesis

A

Splitting the cytoplasm to create two separate diploid cells each with identical chromosomes.

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12
Q

Diffusion

A

movement of particles from a high concentration to a low concentration down a concentration gradient

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13
Q

What is a general rule of SA:V ratios

A

The bigger an object is the smaller it’s surface area to volume ratio will be

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14
Q

Why is SA:V ratio important

A

SA:V ratio large - lot of surface area for diffusion & not much volume to travel through - organisms can get all the substances it needs by simple diffusion

SA:V ratio small - Large multicellular organisms - several layers of cells between centre & environment - useful substances - longer to diffuse in & out, may be used up by outer layers before reaching inner cells.

Therefore, large multicellular organisms need specialised exchange surfaces.

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15
Q

Exchange Surfaces

A

Allow transport in & out of all cells for all the organism’s needs.

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16
Q

Features of an Exchange Surface

A

Large surface area (increase site of exchange)

Thin membrane (decrease diffusion pathway) (distance)

A method of transporting substances to and from the exchange site (e.g. a good blood supply) – maintains a steep concentration gradient (lot of substance in one area and not a lot in another means diffusion will be faster there)

(In animals) being well ventilated for gaseous exchange

17
Q

Gas Exchange in Humans

A

In Alveoli

Oxygen enters lungs & diffuses into bloodstream via capillaries covering the alveoli

Higher concentration of oxygen in the alveoli than blood - oxygen moves into blood

Higher concentration of CO2 in blood than alveoli - CO2 moves out of blood

18
Q

Why is the Alveoli surrounding the lungs a good exchange surface

A

Large SA for Gas Exchange
V. thin – short diffusion distance
Capillaries surround the alveoli - good blood supply. As oxygen is constantly moved away from the lungs - maintains a steep concentration gradient. (it is the same for CO2 leaving the blood)
Moist - gases dissolve to aid efficient diffusion

19
Q

Function & Adaptions of the Villi in the Small Intestine

A

Function - Absorbing the products of digestion

Substances Exchanged - Glucose & Amino Acids

Adaptations - Good blood supply – assists with quick absorption
Cell wall is one layer thick – small diffusion distance
Large SA - increased site of exchange

20
Q

Function & Adaptions of the root of a plant

A

Function - Uptake water from the soil

Substances Exchanged - Water and mineral ions

Adaptations - Roots project deep into the soil - can get to minerals & water
Projections - increase SA
Water constantly moves away from roots - steep concentration gradient

21
Q

Function & Adaptions of the underside of the leaf

A

Function - Gas exchange in plants

Substances Exchanged - Oxygen & CO2

Adaptations - Stomata - small holes - movement of gasses
Flattened shape - Large SA

22
Q

Function & Adaptions of the gills

A

Function - Gas exchange in fish

Substances Exchanged - Oxygen & CO2

Adaptations - Good blood supply - assists w/quick absorption
Thin walls - shorter distance for gasses to diffuse
Gill filaments - Large SA

23
Q

Structure of Lungs

A

Trachea is the long pipe leading into the lungs
The ribs surround the lungs and heart
The intercostal muscles are in-between the rib bones
There is a right and left lung
The heart sits between them both in the middle
The trachea leads into 2 pipes called the left/right main stem bronchus
These main stems branch off into Bronchus’ which then branch of into Bronchioles and at the end of these Bronchioles are Alveoli which are spherical.
The diaphragm sits under the lungs and heart
The Pleural Membrane sits over the chest cavity

24
Q

How do we inhale

A

Diaphragm contracts & flattens/moves down

Intercostal (internal + external) muscles contract

Ribs move up & out

Volume inside the chest increases

Pressure decreases inside the chest & the air pressure outside the chest is higher

Air rushes in

25
Q

How do we exhale

A

Diaphragm relaxes & moves up

Intercostal (internal + external) muscles relax

Ribs down & in

Volume inside the chest decreases

Pressure increases inside the chest & the air pressure outside the chest is now lower

Air leaves the lungs

Biology Y9 (5 decks)

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