B5 revision

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What is a tissue?
A group of specialised cells.
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How does human development happen (3 stages)?
Sperm + egg cell (+fertilisation) = zygote (+division of cells by mitosis) = embryo.
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What is meiosis used for?
Sexual reproduction (the production of gametes).
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What is mitosis used for?
Asexual reproduction (identical copies, clones etc.).
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How many cells does meiosis make?
4 haploid daughter cells.
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How many cells does mitosis make?
2 diploid daughter cells.
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Name two places mitosis happens?
Everywhere in the human body and the meristems of plants.
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Does meiosis or mitosis cause growth?
Mitosis.
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What are the two types of unspecialised (totipotent) cells?
Embryonic stem cells and adult stem cells (bone marrow).
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Does meiosis or mitosis divide the cell nucleus?
Mitosis.
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What do auxins cause?
The elongation of cells.
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Where are auxins produced?
The tip of a plant.
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Where do auxins diffuse?
Auxins diffuse away from the sunlight.
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Why do plants have meristem cells all through their lives?
Because they are unspecialised, so they can be used for growth and repair.
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Why do gardeners often use cuttings for new flowers and plants rather than just using their seeds?
Because the cuttings have identical DNA to the original plant because they are produced through mitosis, whereas the seeds are produced through meiosis and so they have different DNA and aren't identical.
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Why do plants grow towards the light?
Because of phototropism, which is a result of auxins moving down the stem away from the sunlight, so the side that they've moved to grows longer nad the plant therefore faces the sun.
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Put these in size order form smallest to largest: Nucleus, Genes, DNA, Cell, Chromosome?
DNA, Genes, Chromosome, Nucleus, Cell.
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Name two things a cell must copy before it divides?
Organelles (Mitochondria and Ribosomes) and its Nucleus.
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In DNA, which nucleic acids are joined?
C and G, T and A.
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What do the letters stand for?
T = Thymine, A = Adenine, G = Guanine and C = Cystosine.
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What is the first stage of mitosis?
Each chromosome has an identical copy attached to it. The membrane around the nucleus breaks down.
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What is the second stage of mitosis?
The chromosomes move to the centre of the cell.
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What is the third stage of mitosis?
The chromosome copies separate to opposite ends of the cell.
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What is the fourth stage of mitosis?
New nuclear membranes form before the cell divides.
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What is genetic variation?
When offspring are different from their parents and from each other.
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What shape does a DNA strand take?
A double helix.
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How does DNA split and pass on identical information?
Weak bonds between the bases split, unzipping the DNA from one end to the other, making two strands. These new strands then start to form from free bases in the cell.
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What is triplet code?
Three bases on a DNA strand that code for an amino acid.
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What is an mRNA molecule?
A molecule that fits through the pores of a cell to make a copy of the DNA.
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What are the two differences between a DNA and a mRNA?
mRNA has only one strand, and its base pair contains uracil (U) in place of thymine (T).
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Name three proteins and where they are found in the human body?
Keratin (hair, nails and skin), elastin (skin) and collagen (bone, skin, tendons and ligaments).
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What are the properties of keratin?
Strong and insoluble.
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What are the three stages for growing hair?
1) Hair cell genes switch on. 2) Enzymes for making Keratin are made. 3) Hair grows.
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What are the three stages used in a salivary gland cell?
1) Salivary gland cell genes switched on. 2) Amylase is secreted. 3) Starch is digested.
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What is makes an unspecialised cell an unspecialised cell?
All of its genes are switched on.
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What can stem cells be used for?
The treatment of some diseases and the replacement of damaged tissue.
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Name three cells that scientists could produce from stem cells and what they could use them to treat?
Nerve cells (Parkinson's disease), skin cells (burns and ulcers) and retina cells (some kinds of blindness).
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What are adult bone marrow stem cells used to treat?
Leukaemia.
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Other cards in this set

Card 2

Front

How does human development happen (3 stages)?

Back

Sperm + egg cell (+fertilisation) = zygote (+division of cells by mitosis) = embryo.

Card 3

Front

What is meiosis used for?

Back

Preview of the front of card 3

Card 4

Front

What is mitosis used for?

Back

Preview of the front of card 4

Card 5

Front

How many cells does meiosis make?

Back

Preview of the front of card 5
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