Organisation of Living Things Flashcards
1
Q
What is a unicellular organism?
A
- single cell
- usually prokaryotic
- division of labour by organelles
- directly exposed to ext. environment
- short lifespan
- microscopic
- fast reproductive rate
- asexual reproduction
- injury = cell death
- usually uses phagocytosis for nutrients
2
Q
What is a multicellular organism?
A
- made of many cells
- divison of labour - specialised cells
- mostly eukaryotic
- less exposed to ext. - specialised cells for exposure
- long lifespan
- large size
- slow reproductive rate
- sexual reproduction
- can repair/replace cells
- uses heterotrophic/autotrophic methods for nutrients
3
Q
What is a colonial organism?
A
- single cells working together
- division of labour - in a colony and on its own
- usually prokaryotic
- less exposed to ext. env.
- long lifespan
- large size
- intermediate reproductive rate
- asexual & sexual reproduction
3
Q
What is tissue?
A
group of cells of similar structure working together to perform the same function
4
Q
What is an organ?
A
made from different tissues working together to perform specific functions
5
Q
What is an organ system?
A
groups of organs with related functions working together to perform body functions
6
Q
What are 4 types of tissue in animals?
A
- connective (cartilage)
- epithelial (skin, cheek lining, nasal lining)
- muscle
- nervous (brain, nerves)
7
Q
What is an adaptation of the palisade mesophyll?
A
- lots of chloroplasts around edge - gases & light don’t have to travel as far
- more photosynthesis
8
Q
What is an adaptation of the spongy mesophyll layer?
A
- air spaces
- gases can be exchanged & transported freely
9
Q
What is an adaptation of the upper epidermis?
A
- transparent upper layer
- allows light to pass through
10
Q
What is an adaptation of guard cells?
A
- close up when flacid (less water in vacuole) to prevent water loss
- open up when turgid (full vacuole) to allow gases to diffuse
11
Q
What are adaptations of the root hair cell?
A
- thin
- permeable
- high SA
- lots of mitochondria for ATP for active transport
12
Q
How do root hair cells uptake nutrients from the soil?
A
- use ATP for active transport of minerals
- water moves in through osmosis
- oxygen diffuses into cell
13
Q
What are adaptations of the leaf?
A
- wide & large SA for more sunlight
- thin so gases reach cells easily
- veins - carry water to cells & glucose away from cells, support leaves
- stomata - gases move in & out
14
Q
Where is this vascular bundle?
A
Root
15
Q
Where is this vascular bundle?
A
Stem
16
Q
Where is this vascular bundle?
A
Leaf
17
Q
What is an adaptation of the root vascular bundle?
A
lignin in centre xylem provides support for root as it pushes through soil
18
Q
What is an adaptation of the stem vascular bundle?
A
Xylem is on the inside to provide structure (lignin)
19
Q
What are the differences between xylem and phloem?
A
Xylem
* water
* upwards only
* non-living cells
* lignin support in cell walls
Phloem
* sugars
* upwards and downards
* living tissue
* sieve tube elements
* companion cell
20
Q
What are some limiting factors of photosynthesis?
A
- light intensity (plateaus at max point)
- CO₂ conc. (plateaus at max point)
- temperature (reaches optimal point then decr.)
21
Q
What is a source?
A
Location of uptake of sugars
22
Q
What is a sink?
A
Location where sugar is deposited
23
Q
How does the compositon of the transport medium change as it moves around a plant?
A
- sucrose from source → companion cell → phloem
- water from root → xylem
- water in xylem → top of phloem where source is
- sugar and water in phloem moves up and down to companion cell to sink
- excess water in phloem back to xylem
24
How is water transported from the root to the leaf?
* water from root → xylem → leaf transpiration stream
* water shortage from evaporation in leaf pulls up water
* cohesion by hydrogen bonding - water moves in a 'chain'
* adhedes to xylem wall - helps water rise, gravity doesn't pull down
25
How is water lost from the leaf?
* transpiration
* water evaporates from cell surfaces in leaf
* diffuses out via stomata as water vapour
26
What are some factors affecting transpiration rate?
* light intensity (more = faster)
* temperature (hotter = faster)
* wind (windier = faster)
* humidity (dryer = faster)
27
What are 4 types of animals and their gas exchange system?
* insect - tracheal system
* amphibian - skin/lungs/gills
* fish - countercurrent exchange via gills
* mammals - lungs
28
What are adaptations present in gas exchange surfaces?
* thin - gases travel shorter distance
* permeable - substances can easily pass
* highly vascularised - good blood supply to collect O₂
* maintain conc. grad. - O₂ and CO₂ can diffuse down gradient (max diffusion rate)
* large SA - highly branched & folded for inc. diffusion rate
* moist - gases need to dissolve into fluid to cross membrane
* temperature - diffusion is faster in warm conditions
29
Describe mammalian gas exchange
* diaphragm changes pressure in chest
* breathe in air
* intercostal muscles expand
* oxygen diffuses into capillaries from alveoli
* CO₂ diffuses into alveoli from capillaries
* CO₂ breathed out
30
How do alevoli carry out gas exchange effectively?
* capillaries and alveolus are one cell thick - very thin & permeable = fast diffusion
* deoxygenated blood from heart constantly flowing past to become oxygenated
* constantly maintains conc. grad. - blood is always moving
31
Describe the tracheal system
* valves open spiracles
* air enters spiracles
* bristles filter air
* air enters trachea to tracheoles
* air sacs are constantly using O₂ to produce CO₂ to keep conc. grad.
* tidal
32
Describe counter-current exchange
* water enters mouth of fish
* water moves through gills
* water passes next to oxygenated blood first
* water passes next to deoxygenated blood last
* O₂ levels in blood and water move from high to low - maintains conc. gradient
* constant
33
What is an open system?
* Haemolymph free to float through tissues
* simple heart
34
What is a closed system?
* blood stays in blood vessels
* kept moving by heart
35
Compare arteries, veins, and capillaries
Arteries
* thick wall
* carry blood away from heart
* elastic walls
* narrow lumen
* no valves
* very high pressure
Veins
* thin wall
* carry blood towards heart
* less elastic walls
* large lumen
* valves
* very low pressure
Capillaries
* very thin (one cell thick)
* inelastic walls
* very narrow lumen
* no valves
* low pressue
36
Outline the 5 major stages of digestion
1. Ingestion (mouth) - taking food into body
2. Digestion (mouth & stomach) - breaking food into smaller molecules physically & chemically
3. Absorption (small intestine)) - digested food absorbed into blood
4. Assimilation (cells) - use of digested & absorbed food materials for cell respiration/processes
5. Egestion (rectum) - removal of undigested food from body
37
What is the difference between chemical and physical digestion?
* physical - mechanical, change in appearance or location, no new substance
* chemical - new substance, change in property
38
Where is most water absorbed in the digestive system?
small intestine
39
What is the order in which food passes through the digestive system?
1. mouth
2. oesophagus
3. stomach
4. small intestine
5. large intestine
6. rectum
7. anus
40
What does the liver do?
* produces bile
* bile breaks big fat globules into smaller globules by physical digestion
41
What does the gallbladder do?
stores bile
42
What does the pancreas do?
* makes enzyme 'soup'
* enzymes break down large food molecules into smaller molecules
* small molecules can be absorbed into blood
43
How is the small intestine adapted for absorption?
* villi & microvilli for higher SA
* lots of mitochondrion for ATP for active transport
* contains capillary bed for faster absorption
* villi has lacteal for fats to move into
