B4.1-Cell biology Flashcards
What is the role of a ribosome in the cell?
Protein synthesis (making proteins)
What is the role of the mitochondria in the cell?
Mitochondria are the sight of respiration where energy is released
What is the role of cell wall in plant and algal cells?
The cell wall is made of cellulose which strengthens the cell
State 3 differences between plant and animal cells.
- Plant cells have a cell wall and animal cells don’t.
- Plant cells have chloroplasts and animal cells don’t.
- Plant cells have a central vacuole and animal cells don’t.
What is diffusion?
State a function of diffusion in plant and a function of diffusion in animals.
Diffusion is the spreading out of particles from a high concentration to a low concentration.
E.g.
Oxygen diffuses from the lungs into the blood. Carbon dioxide diffuses into leaves.
What is osmosis?
State a function of osmosis in plants and a function of
osmosis in animals.
Osmosis is the diffusion of water from a dilute solution (with a high concentration of water) to a concentrated solution (with a low concentration of water), through a partially permeable membrane.
E.g.
Water osmoses through the roots in a plant.
Water osmoses in the kidney.
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.
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 ÷size of real 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 (including mitosis).
• The DNA replicates to form two copies of each
chromosome.
• Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.
• In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides. Finally the cell divides into two.
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.
What is the function of stem cells in embryos?
In a human embryo, stem cells multiply and differentiate to form the different types of cell in the human body
What is the function of stem cells in adult humans?
Stem cells in adult bone marrow can form many types of cells, including blood cells.
What is the function of stem cells in plants?
Give 2 uses of plant stem cells.
Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant.
Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.
• Rare species can be cloned to protect from extinction.
• Crop plants with special features such as disease
resistance can be cloned to produce large numbers of
identical plants for farmers.
