B4.1-Cell biology part 2 Flashcards
What is active transport?
State a function of active transport in plants and a function in animals.
Active transport moves substances from low to a high
concentration (against a concentration gradient). This requires energy from respiration.
E.g.
Minerals are actively transported into the roots from soil. Some nutrients are actively transported into the blood from the small intestine (sugar)
Name one specialised plant cell and one specialised animal cell. Describe how each one is specialised to do its job.
Plant cells:
Root hair cell – have a large surface area for the uptake of water.
Xylem cell – form a continuous hollow tube, strengthened by lignin.
Phloem cell – elongated cells with pores in the end walls to allow movement of dissolved sugars from the leaves.
Animal cells:
Sperm cells – have a tail to swim to help it move towards the egg.
Nerve cells – is very long to send messages quickly.
Muscle cells – Can contract, making them shorter for movement.
State the equation for magnification
Magnification= size of image ÷ real size of object
Give one advantage and one disadvantage of using an electron microscope instead of a light microscope to view cells.
Advantage:
• Electron microscopes have a higher resolution and
magnification than a light microscope.
Disadvantage:
• Electron microscopes cannot view living material.
Describe the 3 stages of the cell cycle
- Genetic material is doubled and then divided into two identical cells.
- Cell increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.
- One set of chromosomes is pulled to each end of the cell and the nucleus divides.
- The cytoplasm and cell membranes divide to form two identical
cells.
What is a stem cell?
A stem cell is an undifferentiated cell of an organism which can give rise to other types of cell from differentiation.
