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Biology Y9

Terms in this set (69)

Role of ribosomes
site of protein synthesis
role of mitochondria
Site of aerobic respiration, releases energy for respiration
role of the nucleus
Contains DNA, controls in the cell
Role of cytoplasm
Gel-like substance where all chemical reactions take place e
Role of chloroplasts
-contain chlorophyll which absorb light needed for photosynthesis
Body cells grow through cell division, what is the name of this cell division?
- differentiation
-mitosis (correct answer)
- specialisation
Give one difference between the structure of a bacterial cell and an animal cell?
-bacterium cell has cell wall, no nucleus
Describe how the long tail of a sperm cell helps the sperm do its job
-allows the sperm to swim towards the egg
Describe how mitochondria helps a sperm cell do its job
-release energy in respiration
Function of nerve cells
Send electrical impulses around the body
Adaptations of nerve cells
-dendrites which increase the SA so other nerve cells can connect easily
-myelin which insulates the axon and speeds up the transmission of nerve impulses
-axon carries the electrical impulse from one part of the body to another
Function of muscle cells
Contract quickly
Adaptations of muscle cells
-contain protein fibres which ca change length , when muscle cells contracts these protein fibres shorten decreasing the length of the cell
-packed full of mitochondria to release energy for muscle contraction
-muscle cells work together to form muscle tissue
What type of microscope is needed to see ribosomes and mitochondria?
Electron
What is the advantage of using this type of microscope?
-cheaper
-higher magnification (correct answer)
-lower resolution
What are stem cells?
undifferentiated cells that can produce specialised cells and more stem cells
What can stem cells from embryos form?
-can be clones and can be made to differentiate into most different types of human cells
What conditions can stem cell treatment help with?
-diabetes
-paralysis
Two advantages of using stem cells?
-can grow into any type of tissue
-used in medical research
-large numbers can be grown
Disadvantges if using stem cells?
-expensive
-may be rejected
-grow out of control
Through what process do plants use mineral ions from roots into leaves=
...
Define diffusion
The net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient.
Definition of osmosis
Diffusion of water molecules from a region where the water molecules are in a higher concentration to a region where they are in a lower concentration, through a partially permeable membrane.
What is a hypertonic solution?
More concentrated outside the cell than inside the cell
What is a dilute solution?
contains a high concentration of water molecules
What is a concentrated solution
contains a low concentration of water molecules
What would happen if you place an animal cell in water?
-cytoplasm of cells is relatively concentrated so water will move by osmosis from outside the cell into the cell
-this causes the cell to expand and eventually even burst
What would happen if you place an animal cell in a very concentrated solution?
-water will move out of the cell by osmosis
-the cell would shrink
What would happen if a plant cell was placed in water?
-water will move from outside the cells into the cells
-this causes the cell to expand
-the cell wall prevents the cell from bursting, instead the cell becomes swollen and this is called turgid
What would happen if a plant cell was placed in a concentrated solution?
-water would move out of the cell by osmosis
-the cell would shrink and we say it has become flaccid
What word is used to describe a plant cell in a hypertonic solution?
flaccid
What word is used to describe a plant cell in a hypotonic solution?
turgid
Define active tranport
Net movement of particles from an area of low concentration to an area of high concentration against a concentration gradient.
Give two differences between diffusion and active transport?
-Diffusion is down a concentration gradient but active transport is against a concentration gradient
-Diffusion does not require energy from respiration but active transport does require energy from respiration
What is a gene
Small section of DNA on a chromosome
What are chromosomes?
Strands of DNA which carry a large number of genes
How any chromosomes do normal human adult body cells contains?
46 chromosomes, 23 pairs
What happens in the first stage of the cell cycle?
-DNA replicates to form two copes of each chromosome
-the cell also grows and copies its internal such as mitochondria and ribosomes
What happens in the second stage of the cell cycle?
-One set of chromosomes is pulled to each end of the cell
-the nucleus divides
What happens in the final stage of the cell cycle?
-the cytoplasm and cell membrane divided to from two identical cells
Functions of mitosis
-essential for growth and development
-takes place when an organism repairs itself
-happens during asexual reproduction
How many pairs of chromosomes are there in the human body?
23
How any chromsomes are there in a human egg cell?
23
Chromosomes contain genes. From what substance are genes made?
DNA
In the process of mitosis, how do the number of chromosomes in the daughter cells compare to that in the original cell?
the same
Nearly every organism on earth has an even number of chromosomes in its body cells. Suggest why
-inherited one of each pair from each parent
-one of each pair in egg and one of each pair in sperm
What is an ecosystem?
The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of the environment
What is interdependence?
Within a community each species depends on another species for food, shelter, pollination etc. If one species is removed it can have a knock on effect on the whole community
What is a stable community?
Where all species and environmental factors are in balance so the population size remains fairly constant.
What are adaptations?
features that organisms have that enable them to survive in the conditions in which they normally live
In what three ways can adaptations occur?
-structural which are features of an organisms body structure/appearance eg camouflage
-behavioural which is what an organism does eg being nocturnal
-functional which is the way things work inside an organisms body eg producing toxins
What are extremophiles?
Organisms that live in environment that are very extreme such as high temperature, pressure
-eg Bacteria which live in deep sea vents
What are abiotic factors?
Non-living factors in an environment
Examples of abiotic factors
-temperature
-light intensity
-moisture levels
-soil pH
What are biotic factors?
Living factors in an environment
Examples of biotic factors?
-Availability of food
-new predators arriving
-new pathogens
What are enzymes?
globular proteins that act as biological catalysts, seeding up the rate of chemical reactions involved in metabolism.
What is metabolism?
sum of all chemical reactions in the body
What is the lock and key theory?
Enzyme has its own unique active site so it will only bind to one specific substrate so if this substrate doesn't fit the active site the reaction would not be catalysed.
What are proteins made up of?
Long chains of amino acids
What are lipids made up of?
Fatty acids and glycerol
Test for starch
-Place 2cm3 of food solution to a test tube
-Add a few drops of iodine
-if starch is present solution will turn blue-black colour
Test for proteins
-Place 2cm3 of food solution to a test tube
-Add 2cm3 of biuret solution
-if protein is present solution will turn to purple
Test for sugars
-Place 2cm3 of food solution to a test tube
-Add 10 drops of Benedict's solution which is a blue colour
-place test tube into a half-filled beaker of warm water
-if it changes to brick-red a lot of sugar is present
What is the role of digestive enzymes?
Break down large molecules which cannot be absorbed into the bloodstream into smaller, soluble food molecules which can be absorbed by the bloodstream
Role of carbohydrase enzymes
Convert carbohydrates into simple sugars. The amylase is a carbohydrate produced in the salivary glands, pancreas and small intestine that works in the mouth and small intestine to digest starch.
Role of protease enzymes
-catalyse the conversion of proteins into amino acids. They are made in the stomach, pancreas and small intestine and act in the stomach and small intestine
Role of lipase enzymes
-catalyse the conversion of lipids into glycerol and fatty acids. They are made in the pancreas and small intestine and act in the small intestine
What is the role of bile?
-neutralise hydrochloric acid in the stomach to make more suitable pH conditions
-emulsify fats into smaller droplets so they have increased surface area for lipase enzymes to work on.
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