B2 Flash Revision Cards

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Animal cells and plant cells have features in common, such as a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant and algal cells also have a cell wall, and often have chloroplasts and a permanent vacuole.
Bacterial and yeast cells have different structures to animal and plant cells. Dissolved substances pass into and out of cells by diffusion.
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A bacterium is a single-celled organism. A bacterial cell has a different structure to an animal or plant cell. It has cytoplasm, a membrane and a surrounding cell wall, but the genetic material in a bacterial cell is not in a distinct nucleus.
Yeast is a single-celled organism. Like bacterial cells, yeast cells have cytoplasm and a membrane surrounded by a cell wall. But unlike bacterial cells, yeast cells have a nucleus.
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Leaf cell: Function- Absorbs light energy for photosynthesis. Adaption- Packed with chloroplasts. Regular shaped, closely packed cells form a continuous layer for efficient absorption of sunlight.
Root Hair cell: Function- Absorbs water and mineral ions from the soil. Adaption- Long 'finger-like' process with very thin wall, which gives a large surface area.
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Sperm cell: Function- Fertilises an egg cell (female gamete). Adaption- The head contains genetic information and an enzyme to help penetrate the egg cell membrane. The middle section is packed with mitochondria for energy. The tail moves the sperm.
Red Blood cells: Function- Contains haemoglobin to carry oxygen to the cells. Adaption- Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. They have no nucleus.
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Diffusion: Dissolved substances have to pass through the cell membrane to get into or out of a cell. Diffusion is one of the processes that allows this to happen. Diffusion occurs when particles spread.
They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions.
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Organs in animals: Tissues consist of groups of similar cells. Organs contain different tissues, working together to carry out particular functions. Organ systems contain different organs. The different organ systems work together in an organism.
Types of tissues&functions: Muscular tissue- Contracts, bringing about movement. Glandular tissue- Produces substances such as enzymes and hormones. Epithelial tissue- Covers some parts of the body.
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Organs are made of tissues. A particular organ may contain several different tissues. Such as the stomach which contains: Muscular tissues, Glandular tissues and Epithelial tissues.
The stomach is one of the organs that form the digestive system. The stomach contains various tissues, and each tissue is made of a particular type of cell. In order of increasing size and complexity: cells → tissues → organ → organ system.
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Organ systems are groups of organs that carry out a particular function. The human body has several organ systems, including: The nervous system, The respiratory system, The reproductive system and The digestive system.
The Digestive System: Pancreas and salivary glands produce digestive juices. Stomach which digests foods. Liver produces bile. Small Intestine digests&absorbs soluble food. Large Intestine absorbs water from undigested food, producing faeces.
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Plants are multicellular organisms, just like animals. They also usually contain differentiated cells, tissues and organs. Epidermal tissue which covers the plant. Mesophyll carries out photosynthesis. Xylem & phloem take substances around the plant.
Examples of plant organs include: Roots, Stems, and Leaves. REMEMBER: You are likely to be given info, perhaps in a diagram, to help you to explain the adaptations of a particular cell type to its function.
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Thin, waxy cuticle-To protect the leaf without blocking out light. Thin, transparent epidermis-To allow more light to reach the palisade cells. Layer of palisade cells on the top surface- To absorb light.
Many chloroplasts in the palisade cells- To increase absorption of light. Spongy mesophyll inside the leaf- Air spaces allow carbon dioxide to diffuse through the leaf, and increase the surface area.
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Green plants absorb light energy using chlorophyll in their leaves. They use it to react CO2 with water to make a sugar called glucose. The glucose is used in respiration, or converted into starch & stored. Oxygen is produced as a by-product.
This process is called photosynthesis. Temperature, carbon dioxide concentration and light intensity are factors that can limit the rate of photosynthesis.
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Without enough light, a plant cannot photosynthesise quickly, even if there is plenty of water & CO2. Increasing the light intensity will boost the speed of photosynthesis.
Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.
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If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot.
Glucose made in photosynthesis are used in various ways by plants&algae. Storage: Glucose is needed by cells for respiration. But it isn't produced at night when its too dark for PS to happen. They store glucose as in-solubles e.g starch, fat & oils.
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Use: Some glucose is used for respiration to release energy & used to produce: Cellulose - which strengthens the cell wall. Proteins - such as enzymes & chlorophyll. Plants also need nitrates to make proteins & are absorbed from soil as nitrate ions.
The spreading of living organisms in a particular habitat may be affected by physical factors such as temperature & amount of light. Transects & quadrats are used to help collect quantitative data about organisms in their habitats.
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The physical factors that may affect organisms include: Temperature, Amount of light, Availability of water, Availability of nutrients, Availability of oxygen and carbon dioxide.
Habitat- The place where an organism lives. Population- All the members of a species that live in a habitat. Community- All the populations of various organisms that live together in a habitat. Ecosystem- A community & the habitat in which it lives.
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A transect is a line across a habitat or part of a habitat. It can be as simple as a string or rope placed in a line on the ground. The number of organisms of each species can be observed and recorded at regular intervals along the transect.
When using a quadrat: It should be placed randomly so that a representative sample is taken. The validity and reproducibility of the results increases as the results from more quadrats are analysed.
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Proteins are made from long chains of smaller molecules called amino acids. These long chains are folded into particular shapes. This is important in relation to how antibodies and enzymes work.
Enzymes are biological catalysts. There are optimum temperatures and pH values at which their activity is greatest. Enzymes are also proteins. If the shape of an enzyme changes, it may no longer work (it is said to have been 'denatured').
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Enzymes are biological catalysts-stuff that increase the rate of chemical reactions without being used. Enzymes are proteins folded into complex shapes that allow smaller molecules to fit in them. The place where these molecules fit is an active site
If the shape of the enzyme changes, its active site may no longer work. We say the enzyme has been 'denatured'. Enzymes can be denatured by high temperatures or extremes of pH. Although enzymes are made by living things, they are proteins&not alive.
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Different enzymes catalyse different digestion reactions. Digestive Enzymes: Amylase- Starch → sugars. Protease- Proteins → amino acids. Lipase- Lipids → fatty acids + glycerol.
Where they're produced: Amylase- Salivary glands, pancreas, small intestine. Protease- Stomach, pancreas, small intestine. Lipase- Pancreas, small intestine.
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Other cards in this set

Card 2

Front

Yeast is a single-celled organism. Like bacterial cells, yeast cells have cytoplasm and a membrane surrounded by a cell wall. But unlike bacterial cells, yeast cells have a nucleus.

Back

A bacterium is a single-celled organism. A bacterial cell has a different structure to an animal or plant cell. It has cytoplasm, a membrane and a surrounding cell wall, but the genetic material in a bacterial cell is not in a distinct nucleus.

Card 3

Front

Root Hair cell: Function- Absorbs water and mineral ions from the soil. Adaption- Long 'finger-like' process with very thin wall, which gives a large surface area.

Back

Preview of the back of card 3

Card 4

Front

Red Blood cells: Function- Contains haemoglobin to carry oxygen to the cells. Adaption- Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. They have no nucleus.

Back

Preview of the back of card 4

Card 5

Front

They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions.

Back

Preview of the back of card 5
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