BIOLOGY B2 Flashcards
(39 cards)
What’s an organelle?
A specialised unit within a cell which performs a specific function.
What’s a cell?
The basic building block of all living organisms.
What’s a tissue?
A group of cells working together to perform a shared function, and often with similar structure
What’s an organ?
A structure made up of groups of different tissues, working together to perform specific functions.
What’s an organ system?
A group of organs with related functions, working together to perform certain functions within the body.
Small organisms exchange essential substances between themselves over body surfaces.
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True or false? As the volume increases, the surface area increases at the same rate?
False - As volume increases, the surface area doesn’t increase at the same rate
What is the surface area to volume ratio for a 1x1x1cm cube?
Volume = 1x1x1 = 1
Surface area = 6x1x1 = 6
6:1
What’s the surface area to volume ratio for a 2x2x2cm cube and a 3x3x3cm cube?
- Volume = 2x2x2 = 8
Surface area = 6x2x2 = 24
24:8 = 3:1 - Volume = 3x3x3 = 27
Surface area = 6x3x3 = 54
54:27 = 2:1
What are some of the adaptions for exchange surfaces in plants and animals?
- A large surface area
- A short distance required for diffusion
- Good supply of healthy substances
What are the exchange surfaces in the body that have adaptions?
- Villi in the small intestine
- Alveoli in the lungs
- Leaves
Learn the diagram for the human respiration system and gas exchange diagram.
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What do the rings of cartilage around the trachea help with?
Helps to keep the trachea open so that air can be drawn in.
What is the diameter of an alveoli?
Around 300 micrometres
What happens to the following when we inhale?
- Diaphragm
- Rib cage
- External intercostal muscles
- Volume of thorax
- Pressure
- Diaphragm contracts and pulls downwards
- Ribs move up and outwards increasing chest cavity
- External intercostal muscles contract
- The volume of the thorax increases
- Pressure decreases
What happens to the following when we exhale?
- Diaphragm
- Rib cage
- Intercostal muscles
- Volume of the thorax
- Pressure
- Diaphragm relaxes and moves up
- Rib cage relaxes moving down and in decreasing chest cavity
- Intercostal muscles contract
- Volume of the thorax decreases
- Pressure increases
How do fish breathe?
Through the use of gills:
- Water is taken in and passes over the gills and then out under the operculum
- Each gill filament has a network of blood capillaries
- Water flows over the gills flows in the opposite direction to the blood. This is called counter current flow. The exchange of oxygen and carbon dioxide is more efficient than the water and blood both flowing in the same direction.
Why is the exchange of gases in fish efficient?
- The large surface area of the gills
- The large surface area of the blood capillaries in each gill filament
- Short diffusion distance
Why are biological molecules that we consume broken down into our own molecules?
- Most of the molecules in food are too large to pass through the absorbing surface of the gut wall
- The molecules are reassembled in the form required
What do carbohydrates provide for the body?
Main source of energy
What do proteins provide for the body?
Growth and repair
What do lipids provide for the body?
Energy but also makes up part of the cell membrane.
What form is glucose stored in the body as?
In the form of glycogen
What is starch, proteins and lipids broken down into when being digested?
Starch - Glucose
Proteins - Long chains of amino acids
Lipids - Fatty acids ad glycerol
