Life Processes, Cells, and Cell Organisation Flashcards
How do you use a microscope to view slides? (6)
Move the stage (the flat ledge the slide sits on) down to its lowest position.
Place the glass slide onto the stage. Be careful pushing it under the clips that the cover slide doesn’t move or crack.
Select the lowest power objective lens.
Turn the coarse focus knob slowly until you are able to see the cells.
Turn the fine focus knob slowly until the cells are in focus and you can see them clearly.
Repeat steps 1-5 using the higher power magnification to see the cells in more detail.
List and describe the 7 Life Process. (7)
M - Movement - All living things move, even plants
R - Respiration - Getting energy from food
S - Sensitivity - Detecting changes in the surroundings
G - Growth - All living things grow
R - Reproduction - Making more living things of the same type
E - Excretion - Getting rid of waste
N - Nutrition - Taking in and using food
List at least five specialised cells and explain how they are adapted to their function. (10)
Red blood cells carry oxygen around the body, which is needed for respiration.They are well suited to this function because:
They contain haemoglobin, which carries oxygen molecules.
They don’t have a nucleus, allowing more space to carry oxygen.
They are a flat disc shape with dips on both sides (biconcave). This gives them a large surface area, and the best chance of absorbing as much oxygen as they can in the lungs.
Sperm are the male sex cell. They are made in the testes after puberty. They join with an egg cell during fertilisation to form an embryo which can then develop into a new life. The following features make them well suited to this function:
A tail moves them towards an egg cell.
Many mitochondria release energy for movement.
Part of the tip of the head of the sperm, called the acrosome, releases enzymes to digest the egg membrane to allow fertilisation to take place.
The haploid nucleus contains the genetic material for fertilisation.
Sperm are produced in large numbers to increase the chance of fertilisation.
Eggs are the female sex cell. They are made in the ovaries before birth. Usually, one egg is released each month during the menstrual cycle, but sometimes this number may be higher. They join with a sperm cell during fertilisation to form an embryo which can then develop into a new life. They are well suited to this function because:
The egg cell’s cytoplasm contains nutrients for the growth of the early embryo.
The haploid nucleus contains genetic material for fertilisation.
The cell membrane changes after fertilisation by a single sperm so that no more sperm can enter.
Nerve cells transmit electrical signals in the nervous system. They are well suited to their function because:
They are thin, and can be more than one metre long in your spinal cord. This means they can carry messages up and down the body over large distances very quickly.
Nerve cells have branched connections at each end. These join to other nerve cells, allowing them to pass messages around the body.
They have a fatty (myelin) sheath that surrounds them. The fatty sheath increases the speed at which the message can travel.
Muscles cells are found in bundles which make up our muscles. These cells are able to contract (get shorter) and relax (return to original length). There are different types of muscle cell, each perfectly adapted to its function:
Cardiac (heart) muscle cells contract and relax to pump blood around our bodies for our entire lives. They never get tired.
Smooth muscle cells make up thin sheets of muscle, such as the stomach lining. They can also be arranged in bundles, or rings, like that in the anus.
Skeletal muscle is joined to bones. Its cells contract to make bones move and joints bend.
Describe how organisms are organised. (4)
Humans—and other complex multicellular organisms—have systems of organs that work together, carrying out processes that keep us alive.
The body has levels of organization that build on each other. Cells make up tissues, tissues make up organs, and organs make up organ systems.
The function of an organ system depends on the integrated activity of its organs. For instance, digestive system organs cooperate to process food.
The survival of the organism depends on the integrated activity of all the organ systems, often coordinated by the endocrine and nervous systems.
What are the four main plant organs and how are they adapted to their function? (8)
1) Flower
The flower contains the organs of plant sexual reproduction
It attracts insects needed to carry the pollen between plants to allow pollination
It’s really important for reproduction
2) Stem
The stem is the organ which holds the leaves upright in the air and facing the light
It carries water and minerals to the leaves, and food around the plant
The stem is important for nutrition, excretion and growth
3) Leaves
The leaves are the organs of photosynthesis
They make all the food that the plant needs
Leaves contain chlorophyll, which uses light energy to change carbon dioxide and water into glucose
They have tiny little pores, which allow essential carbon dioxide in and waste gases out
Leaves are important for nutrition and excretion
4) Roots
The root is the organ which provides anchorage for the plant so that it does not blow away or fall over
With its root hairs it provides a big surface area to help take in water and minerals from the soil - these are both essential for photosynthesis
The root is therefore important for nutrition
