Cells Flashcards
What is the purpose of the nuclear membrane?
It controls the movement of substances into and out of the nucleus.
What are chromosomes?
Chromosomes are coiled lengths of DNA that carry the genetic information in the form of genes.
The cell membrane is selectively permeable. What does this mean?
It means that some substances can pass through and others cannot.
What structures are typically found in an animal cell?
🚝 Nucleus Nuclear membrane Chromosomes Cytoplasm Cell membrane
What are the four main organs in plants?
Root
Stem
Leaf
Flower
List the three main phases of growth.
Cell division
Cell enlargement
An increase in dry mass
What are the differences between plant and animal growth?
In animals growth occurs all over the body whereas in plants it is restricted to the ends of branches or roots.
In animals growth ceases when an organism reaches a certain size or age whereas in plants growth may continue throughout life.
In animals growth occurs mainly by cell division whereas in plants growth occurs by cell division and cell enlargement.
What are stem cells?
Cells are non-specialised animal cells that can divide by mitosis and differentiate into specialised cells.
What are the two main sources of stem cells?
🚝 Embryonic stem cells - from embryos
🚝 Adult stem cells - from umbilical cord blood and bone marrow.
Why are embryo stem cells better to use than adult stem cells?
🚝 Embryo cells are easier to grow
🚝 Embryo cells can differentiate into any type of cell
🚝 Embryonic stem cells are easier to extract because they are more plentiful
List three reasons why people may object to stem cell research for ethical reasons.
🚝 Some people believe that life begins at conception and so destroying the embryo is murder
🚝 If you believe that life begins at conception then the embryo has human rights
🚝 It might be against their religious views or they might feel like scientists are ‘playing God’ deciding who lives and dies
What are the two most important factors that affect the movement of substances across plasma membranes?
🚝 The size of the particles
🚝 The concentration gradient
What is that diffusion?
Diffusion is the movement of substances from where they are high concentration to where they are in low concentration until evenly distributed.
What is osmosis?
Osmosis is the movement of water from a weak to a strong solution selectively permeable membrane.
What is active uptake?
Active transport or active uptake means that the ions move from where are they are in a lower concentration to where they are in a higher concentration.
