B2 - Cell Structure and Transport Flashcards
Exam revision - Aiming for grade 7 or above.
B2.1 - Aiming for 4 - How many chromosomes are found in the nucleus of human body cells?
46
B2.1 - Aiming for 4 - How many chromosomes are found in the nucleus of gametes?
23
B2.1 - Aiming for 4- What is the meaning of the keywords, mitosis, chromosomes, gene, gametes.
- Mitosis - process of nuclear division in body cells.
- chromosomes - coiled structures made up of DNA.
- gene - short sections of DNA that code for proteins.
- Gametes - A gamete is a sex cell. In humans, gametes are sperm and eggs
B2.1 - Aiming for 6 - Explain why chromosomes are normally found in pairs.
One chromosome is inherited from the mother and one is inherited from the father. The chromosomes in each pair carry the same gene in the same location.
B2.1 - Aiming for 6 - Describe situations where mitosis is occuring.
Whenever more cells are needed. happens throughout the entire lifespan of a living organism (human, animal or plant) but most rapidly during periods of growth.
B2.1 - Aiming for 6 - Describe the process of mitosis using the keywords.
Chromosomes contain genes of male and female parent. Those chromosomes multiply from 2 genes to 4 genes and then divide.
B2.1 - Aiming for 8 - Explain why genetic material must be doubled during mitosis.
the cells separate the duplicated chromosomes into the two daughter cells. In this way the correct inheritance of genetic information from one generation of cells to the next is assured.
B2.1 - Aiming for 8 - Explain in detail what happens at each stage of the cell cycle.
1st: cells grow and increase in mass, replicate DNA and synthesise more organelles. Ribosomes, Mitochondria and sub-cellular structures are produced.
2nd: Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides.
3rd: Cytoplasm and cell membrane divide - two identical daughter cells are produced.
B2.1 - Aiming for 8 - Write a detailed explanation on why mitosis is an important process in living things and how characteristics are inherited.
Chromosomes carry genetic information in DNA. Mitosis ensures that when a cell divides, each new cell produced has the same genetic information.
B2.2 - Aiming for 4 - Define the terms growth and differentiation
Differentiation - The process where a cell becomes specialised to its function.
Growth - an increase in size and mass of a particular organism over a period of time.
B2.2 - Aiming for 4 - State why plant clones are genetically identical to each other.
Plants are cloned to produce identical plants quickly and economically. Clones are genetically identical to the original plant providing the meristem cells
B2.2 - Aiming for 6 - Describe the importance of cell differentiation in multicellular organisms
Differentiated cells are important in a multicellular organism because they are able to perform a specialised function in the body. Multicellular organisms must retain some unspecialised cells that can replenish cells when needed.
B2.2 - Aiming for 6 - Explain how tissue culture creates a clone of a plant
Scientists take a plant they want to clone, divide the plant into tiny pieces. The plant hormones stimulate the plants to grow and develop into fully-grown clones.
B2.2 - Aiming for 8 - Compare and contrast differentiation in plants and animals
In animals the cells differentiate early on and lose the ability to specialise
Only stem cells can specialise
In plant cells – mitosis takes place in the meristems which are found in the shoots and root tops
Plants can differentiate all the way throughout their life
Plants can also CLONE themselves (make identical copies) using asexual reproduction
B2.2 - Aiming for 8 - Explain why it is easier to clone a plant compared to an animal
A plant cell can become any cell the plant needs to survive similar to a stem cell. Cloning animals is a much more complicated process and often comes with birth defects