B5 Flashcards
How do embryonic stem cells develop?
They become tissues and organs in the body, that are specialised for their job
-There are 300 diferent cells by the time you are an adult
Deascribe a growing baby?
Baby takes about a week to reach the 100cell stage
after two months forms organs and is a fetus
How do plants grow?
Plants have cells called meristem cells which are unspecialised, and increase the girtha nd length and height
Why can plants grow back?
This is because meristem cells are unspecialised, meaning they can form into any type of cell, they are stem cells
Where can stem cells be found?
in animals
EG. newts and other reptiles can grow links with unspecialised stem cell throughout their lives
What can meristem cells be used for?
This allows plants to grow when cut or taken away fron the main body of the plant
the cuttind can be dipped in root powder which contains auxins, which stimulates roots to grow asthe meristem cells are stimulated to grow as roots
How do plants adapt to their environment?
Plants lean towards light when placed on windowsills, this is know as phototropism
What cells lose nuclei when it develops?
Red blood cells , lose their nucleus which is then replaced with haemoglobin, the cells develop from stem cells in the bone marrow
How does cell division work?
-It copies DNA aswell as organelles for example: ribosomes + mitochondria
What is mitosis?
Mitosis is the process where cells reproduce.
what is special about gametes?
They have half the amount of DNA as a normal cell.
What is Meosis?
Meosis is the reproduction of sex cells, which occurs in sex organs
Who formulated the modern DNA model
Francis Crick and James Watson in 1935
The rung and ladder model
What is DNA composed of?
A frame of deoxyribose and pshosphates with base pairings inbetween them
How does DNA pass on information?
Weak bond at the end of the strand unzip, leaving two single strands
- free bases then attach to the appropiate bases and two strands of DNA begin to form.
