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Flashcards in Growth And Development Deck (18):

Describe how to make a stained slide of an onion cell

- use tweezers to peel a thin layer of skin tissue from an onion
- place the onion tissue onto a microscope slide on top of distilled water
- add a drop of iodine solution to the tissue and carefully cover the slide
- you should be able to see the parts of an onion cell at X100 magnification


What is growth measured as?

An increase in height, wet mass or dry mas


Describe the process of growth as cell division followed by cells becoming specialised

The cells specialise or differentiate at an early stage into different types of cell to form tissues and organs. All parts of animals grow, but growth eventually stops


When do animals and plants grow?

Animals grow in the early stages of their lives whereas plants grow continually


Understand that all parts of an animal are involved in growth whereas plants grow at specific pars of the plant

Animals - all parts are involved in growth
Plants - grow at specific parts of the plant


Describe the difference between the arrangement of DNA in a bacterial cell and a plant/animal cell

Plant cells keep their DNA inside the nucleus but bacterial cells do not have a nucleus so their DNA floats as circular strands


What do bacterial cells lack?

A 'True' nucleus


What is the best measure of growth?

Dry mass as it is the most accurate method


Describe the main phases of a typical growth curve

Growth in organisms usually follows a typical 's-shaoed' pattern


Identify the rapid growths in humans

In human growth there are two phases of rapid grwoth, one just after brith and the other in adolescence


Explain the advantages and disadvantages of measuring growth by:
- Length
- Wet mass
- Dry mass

L - easy and rapid measurement. Increase in mass might occur with no increase in length
WM - quite easy to measure. Water content of living tissue can be very variable and may give a distorted view overall
DM - most accurate method. Destructive as removal if water kills organisms


Explain why the growth of parts of an organism may differ from the growth rate of the whole organism

This is because the circulation of blood is vital to the growth and development of the embryo and therefore needs to be prioritised


Explain the difference between adult and embryonic stem cells

An embryonic cell can develop into any cell in the body without limit to replenish. And an adult cell is only able to mature into a specialised tissue cell from which tissue the cell is positioned


Explain why plant growth differs from animal growth

- animals tend to grow to a finite size but many plants can grow continuously
- plant cell division is mainly restricted to areas called meristems
- cell enlargement is the main method by which plants gain height
- many plant cells retain the ability to differentiate but most animal cells lose it at an early stage


Discuss issues arising from stem cell research in animals

- embryos have the potential to become a human being, so it is wrong to experiment on them


How can stem cells be obtained and can they be used for?

Stem cells can be obtained from embryonic tissue and could potentially be used to treat medial conditions


What can undifferentiated cells called stem cells develop into?

Different cells, tissues and organs


Describe the functions of the part of a plant cell

- vacuole containing cell sap and providing support
- the cell wall, made of cellulose to provide support