Cell Membrane Flashcards
What are the leaves’ role in a plant?
- The leaves contain most of a plant’s photosynthetic cells
- Photosynthesis requires efficient gas exchange between air surrounding the leaf and the photosynthetic cells, whilst minimising water loss
What is the role of the lungs in mammals?
Gas exchange between air in the alveoli and the blood, to supply cells with oxygen for aerobic respiration and to remove carbon dioxde
What features do exchange surfaces typically have?
- Large surface area to increase rate of diffusion
- Thin wall to provide a short diffusion path
- Dense network of blood vessels to maintain a concentration gradient
How do substances move by active transport?
From a low concentration area to a high concentration area against the concentration gradient
How is the small intestine adapted to it’s role?
- High folded surface lined with specialised intestinal epithelial cells increases surface area
- Only one layer of epithelial cells covers the surface of each villus decreases the diffusion distance
- Each villus has a good blood supply which maintains a concentration gradient
How are the lungs adapted to their role?
- Millions of alveoli collective provide a huge surface area
- The wall of each alveolus is one cell thick, with a moist lining and excellent blood supply which decreases diffusion distance and maintains a concentration gradient
What is a solution?
A solvent and a solute mixed together
How does temperature affect diffusion?
The higher the temperature, the more kinetic energy the particles have. They move faster so there is a higher rate of diffusion.
How do substances move by diffusion?
From an area of high concentration to an area of low concentration, down the concentration gradient
How are the leaves adapted to their role?
- Stomate are tiny openings that predominantly cover the lower side of the leaf, allowing air to circulate inside the leaf, which decreases diffusion distance
- The lower layer of the leaf is made from spongy mesophyll cells which allow air to circulate inside the leaf
What is the role of the roots in plants?
To absorb water and mineral ions from the soil and anchor the plant
What diffuses into the cell?
Oxygen, for aerobic respiration
What kind of membrane does osmosis require?
A selective permeable membrane
What kind of membrane does active transport require?
A selectively permeable membrane
What is a solvent?
The liquid a solid is put into
What is the role of gills in fish?
Gas exchange between water flowing through the gills and the blood, to supply cells with oxygen for aerobic respiration and to remove the waste product carbon dioxide
What substances can move by active transport?
Any substances
Is diffusion a passive or an active process?
Passive process, depending on how much kinetic energy the particles have
Is osmosis a passive or active process?
A passive process that does not require energy
What diffuses out of a cell?
Carbon dioxide, produced by aerobic respiration
What are unicellular organisms?
One cell only
What is the role of the Small Intestine?
Most absorption of digested food molecules into the bloodstream occurs across the wall of the small intestine
How permeable is the cell membrane?
Partially permeable
When an object is larger, is the surface area to volume ration bigger or smaller?
Smaller
How are the gills adapted to their role?
- Each gill made from lots of smaller plates called filaments, which are also covered in projections called lamellae which increases surface area
- A dense capillary network ensure a good blood supply which flows in the opposite direction to water passing through the gills which maintains a concentration gradient
What can move by diffusion?
Small substances, except water
What are multicellular organisms?
Made up of many cells
How does a concentration gradient affect diffusion?
A great concentration gradient gives rise to a higher rate of diffusion
Is active transport an active or a passive process?
It is an active process which requires energy
What is a solute?
A solid that is put into a liquid
How do substances move by osmosis?
From a high water potential area to a low water potential area down the water potential gradient
What substances can move by osmosis?
Water
How does surface area affect diffusion?
A higher surface area gives rise to a higher rate of diffusion
What adaptations do the roots have?
Highly branched to increase surface area
Surface of roots covered in root hair cells, increasing surface area
