B5 Revision
Growth and Development
An accelerated revision resource
A.Blackford
Revision IS important
WARNINGThis PowerPoint is not a substitute for active revision using notes, the workbook and revision guide.
You also need to do plenty of past papers to get exam practice.
Good luck!
Growing and Changing
• We develop as we grow older• Larger animals and plants are built of specialist cells
arranged in particular ways
You need to be able to name examples in each category for animals and plants
Cells Tissues Organs Systems Organisms
Red blood cells
Nerve cells
Palisade cells
Xylem cells
Phloem cells
Xylem tissues
Muscle tissue
Nervous tissue
Blood
Flower
Biceps muscle
Eye
Leaf
Root
Lungs
Root system
Respiratory
Skeletal
Nervous
Digestive
reproductive
Buttercup
House fly
Human
Cat
Dolphin
Earthworm
Oak tree
Single Cell to Fully Grown
• Human fertilised egg cells are called ZYGOTES
• After 10 days the zygote has 100 cells• After 2 months the major organs have
formed• An adult human has about 1014 cells• In plants, growth is at the tips of roots and
shoots in areas called MERISTEMS. There are also meristems to make the stems thicker and in side buds for when they grow
Growing Back• Plant meristem cells are unspecialised and can
continue to grow throughout the plants lifetime.• Newts have spare unspecialised stem cells to allow
them to grow back damaged or lost parts.• Human stem cells are specialised e.g. for skin.• Plants can be grown by using their meristems e.g.
from cuttings. These are dipped in hormone rooting powder containing AUXINS to aid root growth. The new plants are clones.
Nucleus Revision
• Humans have 46 chromosomes (23 pairs one set from mother one set from father)
• Human sex cells have 23 chromosomes• Humans have about 30 000 genes• Genes code for PROTEINS• DNA can make an exact copy of itself• Human red blood cells have no nucleus
DNADNA
Mitosis – For growth and repairInterphase
DNA dividesCell growsOrganelles divide
ProphaseChromosomes has identical copy attached to itChromosomes become visible
MetaphaseChromosomes line up in the equator
AnaphaseChromosome copies separateCopies move to opposite ends of the cell
TelophaseNew nuclear membranes formCytoplasm divides2 identical cells produced (also identical to parent cell)
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Sexual Reproduction
• Involves the fusion of male and female gametes (sex cells)
• From any individual, no two gametes are the same. The chromosomes they have are a mixture of maternal and paternal ones
• Gametes have HALF the number of chromosomes that the rest of the body has
• Gametes are made by MEIOSIS which halves the number of chromosomes.
DNA Structure
• It has a DOUBLE HELIX structure
• There are 4 bases that always pair up in the same way (base pairing)
• Adenosine (A) with Thymine (T)• Guanine (G) with Cytosine (C)• It can make an exact copy of
itself– Weak bonds between the bases
split– A new strand starts to form on
the free bases
Making Proteins
• Proteins are made up of amino acids• There are about 20 possible amino acids to
use• 3 bases on the DNA code for a single amino
acid (triplet code)• mRNA forms on the untwisted DNA • mRNA has Uracil (U) instead of thymine (T)• mRNA moves out of the nucleus through pores• Ribosomes attach to one end of the mRNA and
as they move along amino acids are added to make up the protein
Specialised Proteins
• We have around 300 different specialised cells• Genes are lengths of DNA and they make proteins
Antibodies
Protein Found in Property
KeratinStrong and insoluble
Elastin Skin Springy
Nails, hair skin
Tough but not very stretchy
SkinCollagen
Enzymes All cells, the gut Speed up chemical reactions
Antibodies In the blood Defend against disease
Gene Switching
• The one-gene-one-protein theory• 25 000 – 30 000 genes in humans • In stem cells all these genes are switched
on• As some cells specialise some are switched
off• In the mammalian egg cells proteins are
unevenly distributed therefore one part will become the head and the other the tail
Stem Cells
• Stem cells produced could be used to treat heart disease, diabetes, Parkinson’s and lots more
Phototropism
• Plant stems will grow towards the light. This is PHOTOTROPISM
Plants growing towards the light
Plants grown in normal light. Green and sturdy
Plants grown in the dark. They are CHLOROTIC (yellow) and spindly (ETIOLATED
Auxins at Work
• More auxin goes to the dark side
• Auxin makes the cells grow faster
LIGHTLIGHT
• Conclusion– Auxin is produced
by the tip of the oat seedling
LIGH
TLIG
HT
LIGHTLIGHT